need sleep, continue debugging soon!
[physik/posic.git] / moldyn.c
index ad0f9a3..3608658 100644 (file)
--- a/moldyn.c
+++ b/moldyn.c
 #include "visual/visual.h"
 #include "list/list.h"
 
-int moldyn_usage(char **argv) {
-
-       printf("\n%s usage:\n\n",argv[0]);
-       printf("--- general options ---\n");
-       printf("-E <steps> <file> (log total energy)\n");
-       printf("-M <steps> <file> (log total momentum)\n");
-       printf("-D <steps> <file> (dump total information)\n");
-       printf("-S <steps> <filebase> (single save file)\n");
-       printf("-V <steps> <filebase> (rasmol file)\n");
-       printf("--- physics options ---\n");
-       printf("-T <temperature> [K] (%f)\n",MOLDYN_TEMP);
-       printf("-t <timestep tau> [s] (%.15f)\n",MOLDYN_TAU);
-       printf("-C <cutoff radius> [m] (%.15f)\n",MOLDYN_CUTOFF);
-       printf("-R <runs> (%d)\n",MOLDYN_RUNS);
-       printf(" -- integration algo --\n");
-       printf("  -I <number> (%d)\n",MOLDYN_INTEGRATE_DEFAULT);
-       printf("     0: velocity verlet\n");
-       printf(" -- potential --\n");
-       printf("  -P <number> <param1 param2 ...>\n");
-       printf("     0: harmonic oscillator\n");
-       printf("        param1: spring constant\n");
-       printf("        param2: equilibrium distance\n");
-       printf("     1: lennard jones\n");
-       printf("        param1: epsilon\n");
-       printf("        param2: sigma\n");
-       printf("\n");
+
+int moldyn_init(t_moldyn *moldyn,int argc,char **argv) {
+
+       //int ret;
+
+       //ret=moldyn_parse_argv(moldyn,argc,argv);
+       //if(ret<0) return ret;
+
+       memset(moldyn,0,sizeof(t_moldyn));
+
+       rand_init(&(moldyn->random),NULL,1);
+       moldyn->random.status|=RAND_STAT_VERBOSE;
 
        return 0;
 }
 
-int moldyn_parse_argv(t_moldyn *moldyn,int argc,char **argv) {
+int moldyn_shutdown(t_moldyn *moldyn) {
 
-       int i;
-       t_ho_params hop;
-       t_lj_params ljp;
-       double s,e;
+       printf("[moldyn] shutdown\n");
+       moldyn_log_shutdown(moldyn);
+       link_cell_shutdown(moldyn);
+       rand_close(&(moldyn->random));
+       free(moldyn->atom);
 
-       memset(moldyn,0,sizeof(t_moldyn));
+       return 0;
+}
+
+int set_int_alg(t_moldyn *moldyn,u8 algo) {
 
-       /* default values */
-       moldyn->t=MOLDYN_TEMP;
-       moldyn->tau=MOLDYN_TAU;
-       moldyn->time_steps=MOLDYN_RUNS;
-       moldyn->integrate=velocity_verlet;
-       moldyn->potential_force_function=lennard_jones;
-
-       /* parse argv */
-       for(i=1;i<argc;i++) {
-               if(argv[i][0]=='-') {
-                       switch(argv[i][1]){
-                               case 'E':
-                                       moldyn->ewrite=atoi(argv[++i]);
-                                       strncpy(moldyn->efb,argv[++i],64);
-                                       break;
-                               case 'M':
-                                       moldyn->mwrite=atoi(argv[++i]);
-                                       strncpy(moldyn->mfb,argv[++i],64);
-                                       break;
-                               case 'D':
-                                       moldyn->dwrite=atoi(argv[++i]);
-                                       strncpy(moldyn->dfb,argv[++i],64);
-                                       break;
-                               case 'S':
-                                       moldyn->swrite=atoi(argv[++i]);
-                                       strncpy(moldyn->sfb,argv[++i],64);
-                                       break;
-                               case 'V':
-                                       moldyn->vwrite=atoi(argv[++i]);
-                                       strncpy(moldyn->vfb,argv[++i],64);
-                                       break;
-                               case 'T':
-                                       moldyn->t=atof(argv[++i]);
-                                       break;
-                               case 't':
-                                       moldyn->tau=atof(argv[++i]);
-                                       break;
-                               case 'C':
-                                       moldyn->cutoff=atof(argv[++i]);
-                                       break;
-                               case 'R':
-                                       moldyn->time_steps=atoi(argv[++i]);
-                                       break;
-                               case 'I':
-       /* integration algorithm */
-       switch(atoi(argv[++i])) {
+       switch(algo) {
                case MOLDYN_INTEGRATE_VERLET:
                        moldyn->integrate=velocity_verlet;
                        break;
                default:
-                       printf("unknown integration algo %s\n",argv[i]);
-                       moldyn_usage(argv);
+                       printf("unknown integration algorithm: %02x\n",algo);
                        return -1;
        }
 
-                               case 'P':
-       /* potential + params */
-       switch(atoi(argv[++i])) {
-               case MOLDYN_POTENTIAL_HO:
-                       hop.spring_constant=atof(argv[++i]);
-                       hop.equilibrium_distance=atof(argv[++i]);
-                       moldyn->pot_params=malloc(sizeof(t_ho_params));
-                       memcpy(moldyn->pot_params,&hop,sizeof(t_ho_params));
-                       moldyn->potential_force_function=harmonic_oscillator;
-                       break;
-               case MOLDYN_POTENTIAL_LJ:
-                       e=atof(argv[++i]);
-                       s=atof(argv[++i]);
-                       ljp.epsilon4=4*e;
-                       ljp.sigma6=s*s*s*s*s*s;
-                       ljp.sigma12=ljp.sigma6*ljp.sigma6;
-                       moldyn->pot_params=malloc(sizeof(t_lj_params));
-                       memcpy(moldyn->pot_params,&ljp,sizeof(t_lj_params));
-                       moldyn->potential_force_function=lennard_jones;
-                       break;
-               default:
-                       printf("unknown potential %s\n",argv[i]);
-                       moldyn_usage(argv);
-                       return -1;
-       }
+       return 0;
+}
 
-                               default:
-                                       printf("unknown option %s\n",argv[i]);
-                                       moldyn_usage(argv);
-                                       return -1;
-                       }
-               } else {
-                       moldyn_usage(argv);
-                       return -1;
-               }
-       }
+int set_cutoff(t_moldyn *moldyn,double cutoff) {
+
+       moldyn->cutoff=cutoff;
 
        return 0;
 }
 
-int moldyn_log_init(t_moldyn *moldyn) {
+int set_temperature(t_moldyn *moldyn,double t_ref) {
 
-       moldyn->lvstat=0;
-       t_visual *vis;
+       moldyn->t_ref=t_ref;
 
-       vis=&(moldyn->vis);
+       return 0;
+}
 
-       if(moldyn->ewrite) {
-               moldyn->efd=open(moldyn->efb,O_WRONLY|O_CREAT|O_TRUNC);
-               if(moldyn->efd<0) {
-                       perror("[moldyn] efd open");
-                       return moldyn->efd;
-               }
-               dprintf(moldyn->efd,"# moldyn total energy logfile\n");
-               moldyn->lvstat|=MOLDYN_LVSTAT_TOTAL_E;
-       }
+int set_pt_scale(t_moldyn *moldyn,u8 ptype,double ptc,u8 ttype,double ttc) {
 
-       if(moldyn->mwrite) {
-               moldyn->mfd=open(moldyn->mfb,O_WRONLY|O_CREAT|O_TRUNC);
-               if(moldyn->mfd<0) {
-                       perror("[moldyn] mfd open");
-                       return moldyn->mfd;
-               }
-               dprintf(moldyn->mfd,"# moldyn total momentum logfile\n");
-               moldyn->lvstat|=MOLDYN_LVSTAT_TOTAL_M;
-       }
+       moldyn->pt_scale=(ptype|ttype);
+       moldyn->t_tc=ttc;
+       moldyn->p_tc=ptc;
 
-       if(moldyn->swrite)
-               moldyn->lvstat|=MOLDYN_LVSTAT_SAVE;
+       return 0;
+}
 
-       if(moldyn->dwrite) {
-               moldyn->dfd=open(moldyn->dfb,O_WRONLY|O_CREAT|O_TRUNC);
-                if(moldyn->dfd<0) {
-                       perror("[moldyn] dfd open");
-                       return moldyn->dfd;
-               }
-               write(moldyn->dfd,moldyn,sizeof(t_moldyn));
-               moldyn->lvstat|=MOLDYN_LVSTAT_DUMP;
-       }
+int set_dim(t_moldyn *moldyn,double x,double y,double z,u8 visualize) {
+
+       moldyn->dim.x=x;
+       moldyn->dim.y=y;
+       moldyn->dim.z=z;
 
-       if((moldyn->vwrite)&&(vis)) {
-               moldyn->visual=vis;
-               visual_init(vis,moldyn->vfb);
-               moldyn->lvstat|=MOLDYN_LVSTAT_VISUAL;
+       if(visualize) {
+               moldyn->vis.dim.x=x;
+               moldyn->vis.dim.y=y;
+               moldyn->vis.dim.z=z;
        }
 
-       moldyn->lvstat|=MOLDYN_LVSTAT_INITIALIZED;
+       return 0;
+}
+
+int set_nn_dist(t_moldyn *moldyn,double dist) {
+
+       moldyn->nnd=dist;
 
        return 0;
 }
 
-int moldyn_log_shutdown(t_moldyn *moldyn) {
+int set_pbc(t_moldyn *moldyn,u8 x,u8 y,u8 z) {
 
-       if(moldyn->efd) close(moldyn->efd);
-       if(moldyn->mfd) close(moldyn->efd);
-       if(moldyn->dfd) close(moldyn->efd);
-       if(moldyn->visual) visual_tini(moldyn->visual);
+       if(x)
+               moldyn->status|=MOLDYN_STAT_PBX;
+
+       if(y)
+               moldyn->status|=MOLDYN_STAT_PBY;
+
+       if(z)
+               moldyn->status|=MOLDYN_STAT_PBZ;
 
        return 0;
 }
 
-int moldyn_init(t_moldyn *moldyn,int argc,char **argv) {
+int set_potential1b(t_moldyn *moldyn,pf_func1b func,void *params) {
 
-       int ret;
+       moldyn->func1b=func;
+       moldyn->pot1b_params=params;
+
+       return 0;
+}
 
-       ret=moldyn_parse_argv(moldyn,argc,argv);
-       if(ret<0) return ret;
+int set_potential2b(t_moldyn *moldyn,pf_func2b func,void *params) {
 
-       ret=moldyn_log_init(moldyn);
-       if(ret<0) return ret;
+       moldyn->func2b=func;
+       moldyn->pot2b_params=params;
 
-       rand_init(&(moldyn->random),NULL,1);
-       moldyn->random.status|=RAND_STAT_VERBOSE;
+       return 0;
+}
+
+int set_potential2b_post(t_moldyn *moldyn,pf_func2b_post func,void *params) {
 
-       moldyn->status=0;
+       moldyn->func2b_post=func;
+       moldyn->pot2b_params=params;
 
        return 0;
 }
 
-int moldyn_shutdown(t_moldyn *moldyn) {
+int set_potential3b(t_moldyn *moldyn,pf_func3b func,void *params) {
 
-       moldyn_log_shutdown(moldyn);
-       rand_close(&(moldyn->random));
-       free(moldyn->atom);
+       moldyn->func3b=func;
+       moldyn->pot3b_params=params;
 
        return 0;
 }
 
-int create_lattice(unsigned char type,int element,double mass,double lc,
-                   int a,int b,int c,t_atom **atom) {
+int moldyn_set_log(t_moldyn *moldyn,u8 type,char *fb,int timer) {
+
+       switch(type) {
+               case LOG_TOTAL_ENERGY:
+                       moldyn->ewrite=timer;
+                       moldyn->efd=open(fb,O_WRONLY|O_CREAT|O_TRUNC);
+                       if(moldyn->efd<0) {
+                               perror("[moldyn] efd open");
+                               return moldyn->efd;
+                       }
+                       dprintf(moldyn->efd,"# total energy log file\n");
+                       break;
+               case LOG_TOTAL_MOMENTUM:
+                       moldyn->mwrite=timer;
+                       moldyn->mfd=open(fb,O_WRONLY|O_CREAT|O_TRUNC);
+                       if(moldyn->mfd<0) {
+                               perror("[moldyn] mfd open");
+                               return moldyn->mfd;
+                       }
+                       dprintf(moldyn->efd,"# total momentum log file\n");
+                       break;
+               case SAVE_STEP:
+                       moldyn->swrite=timer;
+                       strncpy(moldyn->sfb,fb,63);
+                       break;
+               case VISUAL_STEP:
+                       moldyn->vwrite=timer;
+                       strncpy(moldyn->vfb,fb,63);
+                       visual_init(&(moldyn->vis),fb);
+                       break;
+               default:
+                       printf("unknown log mechanism: %02x\n",type);
+                       return -1;
+       }
+
+       return 0;
+}
+
+int moldyn_log_shutdown(t_moldyn *moldyn) {
+
+       printf("[moldyn] log shutdown\n");
+       if(moldyn->efd) close(moldyn->efd);
+       if(moldyn->mfd) close(moldyn->mfd);
+       if(&(moldyn->vis)) visual_tini(&(moldyn->vis));
+
+       return 0;
+}
+
+int create_lattice(t_moldyn *moldyn,u8 type,double lc,int element,double mass,
+                   u8 attr,u8 bnum,int a,int b,int c) {
 
        int count;
        int ret;
@@ -255,10 +213,11 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
        count=a*b*c;
 
        if(type==FCC) count*=4;
+
        if(type==DIAMOND) count*=8;
 
-       *atom=malloc(count*sizeof(t_atom));
-       if(*atom==NULL) {
+       moldyn->atom=malloc(count*sizeof(t_atom));
+       if(moldyn->atom==NULL) {
                perror("malloc (atoms)");
                return -1;
        }
@@ -267,10 +226,10 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
 
        switch(type) {
                case FCC:
-                       ret=fcc_init(a,b,c,lc,*atom,&origin);
+                       ret=fcc_init(a,b,c,lc,moldyn->atom,&origin);
                        break;
                case DIAMOND:
-                       ret=diamond_init(a,b,c,lc,*atom,&origin);
+                       ret=diamond_init(a,b,c,lc,moldyn->atom,&origin);
                        break;
                default:
                        printf("unknown lattice type (%02x)\n",type);
@@ -285,23 +244,58 @@ int create_lattice(unsigned char type,int element,double mass,double lc,
                return -1;
        }
 
+       moldyn->count=count;
+       printf("[moldyn] created lattice with %d atoms\n",count);
+
        while(count) {
-               (*atom)[count-1].element=element;
-               (*atom)[count-1].mass=mass;
                count-=1;
+               moldyn->atom[count].element=element;
+               moldyn->atom[count].mass=mass;
+               moldyn->atom[count].attr=attr;
+               moldyn->atom[count].bnum=bnum;
+               check_per_bound(moldyn,&(moldyn->atom[count].r));
        }
 
+
        return ret;
 }
 
-int destroy_lattice(t_atom *atom) {
+int add_atom(t_moldyn *moldyn,int element,double mass,u8 bnum,u8 attr,
+             t_3dvec *r,t_3dvec *v) {
+
+       t_atom *atom;
+       void *ptr;
+       int count;
+       
+       atom=moldyn->atom;
+       count=++(moldyn->count);
+
+       ptr=realloc(atom,count*sizeof(t_atom));
+       if(!ptr) {
+               perror("[moldyn] realloc (add atom)");
+               return -1;
+       }
+       moldyn->atom=ptr;
+
+       atom=moldyn->atom;
+       atom[count-1].r=*r;
+       atom[count-1].v=*v;
+       atom[count-1].element=element;
+       atom[count-1].mass=mass;
+       atom[count-1].bnum=bnum;
+       atom[count-1].attr=attr;
+
+       return 0;
+}
+
+int destroy_atoms(t_moldyn *moldyn) {
 
-       if(atom) free(atom);
+       if(moldyn->atom) free(moldyn->atom);
 
        return 0;
 }
 
-int thermal_init(t_moldyn *moldyn) {
+int thermal_init(t_moldyn *moldyn,u8 equi_init) {
 
        /*
         * - gaussian distribution of velocities
@@ -321,7 +315,7 @@ int thermal_init(t_moldyn *moldyn) {
        /* gaussian distribution of velocities */
        v3_zero(&p_total);
        for(i=0;i<moldyn->count;i++) {
-               sigma=sqrt(2.0*K_BOLTZMANN*moldyn->t/atom[i].mass);
+               sigma=sqrt(2.0*K_BOLTZMANN*moldyn->t_ref/atom[i].mass);
                /* x direction */
                v=sigma*rand_get_gauss(random);
                atom[i].v.x=v;
@@ -344,44 +338,75 @@ int thermal_init(t_moldyn *moldyn) {
        }
 
        /* velocity scaling */
-       scale_velocity(moldyn);
+       scale_velocity(moldyn,equi_init);
 
        return 0;
 }
 
-int scale_velocity(t_moldyn *moldyn) {
+int scale_velocity(t_moldyn *moldyn,u8 equi_init) {
 
        int i;
-       double e,c;
+       double e,scale;
        t_atom *atom;
+       int count;
 
        atom=moldyn->atom;
 
        /*
         * - velocity scaling (E = 3/2 N k T), E: kinetic energy
         */
+
+       /* get kinetic energy / temperature & count involved atoms */
        e=0.0;
+       count=0;
+       for(i=0;i<moldyn->count;i++) {
+               if((equi_init&TRUE)||(atom[i].attr&ATOM_ATTR_HB)) {
+                       e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
+                       count+=1;
+               }
+       }
+       if(count!=0) moldyn->t=(2.0*e)/(3.0*count*K_BOLTZMANN);
+       else return 0;  /* no atoms involved in scaling! */
+       
+       /* (temporary) hack for e,t = 0 */
+       if(e==0.0) {
+       moldyn->t=0.0;
+               if(moldyn->t_ref!=0.0)
+                       thermal_init(moldyn,equi_init);
+               else
+                       return 0; /* no scaling needed */
+       }
+
+
+       /* get scaling factor */
+       scale=moldyn->t_ref/moldyn->t;
+       if(equi_init&TRUE)
+               scale*=2.0;
+       else
+               if(moldyn->pt_scale&T_SCALE_BERENDSEN)
+                       scale=1.0+moldyn->tau*(scale-1.0)/moldyn->t_tc;
+       scale=sqrt(scale);
+
+       /* velocity scaling */
        for(i=0;i<moldyn->count;i++)
-               e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
-       c=sqrt((2.0*e)/(3.0*moldyn->count*K_BOLTZMANN*moldyn->t));
-       for(i=0;i<moldyn->count;i++)
-               v3_scale(&(atom[i].v),&(atom[i].v),(1.0/c));
+               if((equi_init&TRUE)||(atom[i].attr&ATOM_ATTR_HB))
+                       v3_scale(&(atom[i].v),&(atom[i].v),scale);
 
        return 0;
 }
 
-double get_e_kin(t_atom *atom,int count) {
+double get_e_kin(t_moldyn *moldyn) {
 
        int i;
-       double e;
+       t_atom *atom;
 
-       e=0.0;
+       atom=moldyn->atom;
+       moldyn->ekin=0.0;
 
-       for(i=0;i<count;i++) {
-               e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
-       }
+       for(i=0;i<moldyn->count;i++)
+               moldyn->ekin+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
 
-       return e;
+       return moldyn->ekin;
 }
 
 double get_e_pot(t_moldyn *moldyn) {
@@ -389,23 +414,26 @@ double get_e_pot(t_moldyn *moldyn) {
        return moldyn->energy;
 }
 
-double get_total_energy(t_moldyn *moldyn) {
+double update_e_kin(t_moldyn *moldyn) {
 
-       double e;
+       return(get_e_kin(moldyn));
+}
 
-       e=get_e_kin(moldyn->atom,moldyn->count);
-       e+=get_e_pot(moldyn);
+double get_total_energy(t_moldyn *moldyn) {
 
-       return e;
+       return(moldyn->ekin+moldyn->energy);
 }
 
-t_3dvec get_total_p(t_atom *atom, int count) {
+t_3dvec get_total_p(t_moldyn *moldyn) {
 
        t_3dvec p,p_total;
        int i;
+       t_atom *atom;
+
+       atom=moldyn->atom;
 
        v3_zero(&p_total);
-       for(i=0;i<count;i++) {
+       for(i=0;i<moldyn->count;i++) {
                v3_scale(&p,&(atom[i].v),atom[i].mass);
                v3_add(&p_total,&p_total,&p);
        }
@@ -413,15 +441,19 @@ t_3dvec get_total_p(t_atom *atom, int count) {
        return p_total;
 }
 
-double estimate_time_step(t_moldyn *moldyn,double nn_dist,double t) {
+double estimate_time_step(t_moldyn *moldyn,double nn_dist) {
 
        double tau;
 
-       tau=0.05*nn_dist/(sqrt(3.0*K_BOLTZMANN*t/moldyn->atom[0].mass));
-       tau*=1.0E-9;
-       if(tau<moldyn->tau)
-               printf("[moldyn] warning: time step  (%f > %.15f)\n",
-                      moldyn->tau,tau);
+       /* nn_dist is the nearest neighbour distance */
+
+       if(moldyn->t==5.0) {
+               printf("[moldyn] i do not estimate timesteps below %f K!\n",
+                      MOLDYN_CRITICAL_EST_TEMP);
+               return 23.42;
+       }
+
+       tau=(0.05*nn_dist*moldyn->atom[0].mass)/sqrt(3.0*K_BOLTZMANN*moldyn->t);
 
        return tau;     
 }
@@ -436,11 +468,11 @@ int link_cell_init(t_moldyn *moldyn) {
 
        t_linkcell *lc;
        int i;
+       int fd;
 
-       lc=&(moldyn->lc);
+       fd=open("/dev/null",O_WRONLY);
 
-       /* list log fd */
-       lc->listfd=open("/dev/null",O_WRONLY);
+       lc=&(moldyn->lc);
 
        /* partitioning the md cell */
        lc->nx=moldyn->dim.x/moldyn->cutoff;
@@ -453,11 +485,11 @@ int link_cell_init(t_moldyn *moldyn) {
        lc->cells=lc->nx*lc->ny*lc->nz;
        lc->subcell=malloc(lc->cells*sizeof(t_list));
 
-       printf("initializing linked cells (%d)\n",lc->cells);
+       printf("[moldyn] initializing linked cells (%d)\n",lc->cells);
 
        for(i=0;i<lc->cells;i++)
                //list_init(&(lc->subcell[i]),1);
-               list_init(&(lc->subcell[i]));
+               list_init(&(lc->subcell[i]),fd);
 
        link_cell_update(moldyn);
        
@@ -500,7 +532,7 @@ int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
        int ci,cj,ck;
        int nx,ny,nz;
        int x,y,z;
-       unsigned char bx,by,bz;
+       u8 bx,by,bz;
 
        lc=&(moldyn->lc);
        nx=lc->nx;
@@ -510,7 +542,6 @@ int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
        count2=27;
        a=nx*ny;
 
-
        cell[0]=lc->subcell[i+j*nx+k*a];
        for(ci=-1;ci<=1;ci++) {
                bx=0;
@@ -544,7 +575,9 @@ int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
                }
        }
 
-       return count2;
+       lc->dnlc=count1;
+
+       return count1;
 }
 
 int link_cell_shutdown(t_moldyn *moldyn) {
@@ -557,8 +590,42 @@ int link_cell_shutdown(t_moldyn *moldyn) {
        for(i=0;i<lc->nx*lc->ny*lc->nz;i++)
                list_shutdown(&(moldyn->lc.subcell[i]));
 
-       if(lc->listfd) close(lc->listfd);
+       return 0;
+}
+
+int moldyn_add_schedule(t_moldyn *moldyn,int runs,double tau) {
+
+       int count;
+       void *ptr;
+       t_moldyn_schedule *schedule;
+
+       schedule=&(moldyn->schedule);
+       count=++(schedule->content_count);
+
+       ptr=realloc(moldyn->schedule.runs,count*sizeof(int));
+       if(!ptr) {
+               perror("[moldyn] realloc (runs)");
+               return -1;
+       }
+       moldyn->schedule.runs=ptr;
+       moldyn->schedule.runs[count-1]=runs;
+
+       ptr=realloc(schedule->tau,count*sizeof(double));
+       if(!ptr) {
+               perror("[moldyn] realloc (tau)");
+               return -1;
+       }
+       moldyn->schedule.tau=ptr;
+       moldyn->schedule.tau[count-1]=tau;
+
+       return 0;
+}
+
+int moldyn_set_schedule_hook(t_moldyn *moldyn,void *hook,void *hook_params) {
 
+       moldyn->schedule.hook=hook;
+       moldyn->schedule.hook_params=hook_params;
+       
        return 0;
 }
 
@@ -572,12 +639,17 @@ int link_cell_shutdown(t_moldyn *moldyn) {
 
 int moldyn_integrate(t_moldyn *moldyn) {
 
-       int i;
-       unsigned int e,m,s,d,v;
+       int i,sched;
+       unsigned int e,m,s,v;
        t_3dvec p;
-
+       t_moldyn_schedule *schedule;
+       t_atom *atom;
        int fd;
        char fb[128];
+       double ds;
+
+       schedule=&(moldyn->schedule);
+       atom=moldyn->atom;
 
        /* initialize linked cell method */
        link_cell_init(moldyn);
@@ -586,38 +658,68 @@ int moldyn_integrate(t_moldyn *moldyn) {
        e=moldyn->ewrite;
        m=moldyn->mwrite;
        s=moldyn->swrite;
-       d=moldyn->dwrite;
        v=moldyn->vwrite;
 
-       if(!(moldyn->lvstat&MOLDYN_LVSTAT_INITIALIZED)) {
-               printf("[moldyn] warning, lv system not initialized\n");
-               return -1;
-       }
-
        /* sqaure of some variables */
        moldyn->tau_square=moldyn->tau*moldyn->tau;
        moldyn->cutoff_square=moldyn->cutoff*moldyn->cutoff;
 
        /* calculate initial forces */
-       moldyn->potential_force_function(moldyn);
+       potential_force_calc(moldyn);
+
+       /* some stupid checks before we actually start calculating bullshit */
+       if(moldyn->cutoff>0.5*moldyn->dim.x)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.x\n");
+       if(moldyn->cutoff>0.5*moldyn->dim.y)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.y\n");
+       if(moldyn->cutoff>0.5*moldyn->dim.z)
+               printf("[moldyn] warning: cutoff > 0.5 x dim.z\n");
+       ds=0.5*atom[0].f.x*moldyn->tau_square/atom[0].mass;
+       if(ds>0.05*moldyn->nnd)
+               printf("[moldyn] warning: forces too high / tau too small!\n");
+
+       /* zero absolute time */
+       moldyn->time=0.0;
+
+       /* debugging, ignre */
+       moldyn->debug=0;
+
+       /* executing the schedule */
+       for(sched=0;sched<moldyn->schedule.content_count;sched++) {
+
+               /* setting amount of runs and finite time step size */
+               moldyn->tau=schedule->tau[sched];
+               moldyn->tau_square=moldyn->tau*moldyn->tau;
+               moldyn->time_steps=schedule->runs[sched];
+
+       /* integration according to schedule */
 
        for(i=0;i<moldyn->time_steps;i++) {
 
                /* integration step */
                moldyn->integrate(moldyn);
 
+               /* p/t scaling */
+               if(moldyn->pt_scale&(T_SCALE_BERENDSEN|T_SCALE_DIRECT))
+                       scale_velocity(moldyn,FALSE);
+
+               /* increase absolute time */
+               moldyn->time+=moldyn->tau;
+
                /* check for log & visualization */
                if(e) {
                        if(!(i%e))
                                dprintf(moldyn->efd,
-                                       "%.15f %.45f\n",i*moldyn->tau,
+                                       "%.15f %.45f %.45f %.45f\n",
+                                       moldyn->time,update_e_kin(moldyn),
+                                       moldyn->energy,
                                        get_total_energy(moldyn));
                }
                if(m) {
                        if(!(i%m)) {
-                               p=get_total_p(moldyn->atom,moldyn->count);
+                               p=get_total_p(moldyn);
                                dprintf(moldyn->mfd,
-                                       "%.15f %.45f\n",i*moldyn->tau,
+                                       "%.15f %.45f\n",moldyn->time,
                                        v3_norm(&p));
                        }
                }
@@ -632,22 +734,28 @@ int moldyn_integrate(t_moldyn *moldyn) {
                                        write(fd,moldyn->atom,
                                              moldyn->count*sizeof(t_atom));
                                }
+                               close(fd);
                        }       
                }
-               if(d) {
-                       if(!(i%d))
-                               write(moldyn->dfd,moldyn->atom,
-                                     moldyn->count*sizeof(t_atom));
-
-               }
                if(v) {
                        if(!(i%v)) {
-                               visual_atoms(moldyn->visual,i*moldyn->tau,
+                               visual_atoms(&(moldyn->vis),moldyn->time,
                                             moldyn->atom,moldyn->count);
-                               printf("\rsteps: %d",i);
+                               printf("\rsched: %d, steps: %d, theta: %d",
+                                      sched,i,moldyn->debug);
                                fflush(stdout);
                        }
                }
+
+       }
+
+               /* check for hooks */
+               if(schedule->hook)
+                       schedule->hook(moldyn,schedule->hook_params);
+
+               /* get a new info line */
+               printf("\n");
+
        }
 
        return 0;
@@ -673,7 +781,7 @@ int velocity_verlet(t_moldyn *moldyn) {
                v3_add(&(atom[i].r),&(atom[i].r),&delta);
                v3_scale(&delta,&(atom[i].f),0.5*tau_square/atom[i].mass);
                v3_add(&(atom[i].r),&(atom[i].r),&delta);
-               v3_per_bound(&(atom[i].r),&(moldyn->dim));
+               check_per_bound(moldyn,&(atom[i].r));
 
                /* velocities */
                v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
@@ -681,14 +789,10 @@ int velocity_verlet(t_moldyn *moldyn) {
        }
 
        /* neighbour list update */
-printf("list update ...\n");
        link_cell_update(moldyn);
-printf("done\n");
 
        /* forces depending on chosen potential */
-printf("calc potential/force ...\n");
-       moldyn->potential_force_function(moldyn);
-printf("done\n");
+       potential_force_calc(moldyn);
 
        for(i=0;i<count;i++) {
                /* again velocities */
@@ -706,593 +810,628 @@ printf("done\n");
  * 
  */
 
-/* harmonic oscillator potential and force */
+/* generic potential and force calculation */
 
-int harmonic_oscillator(t_moldyn *moldyn) {
+int potential_force_calc(t_moldyn *moldyn) {
 
-       t_ho_params *params;
-       t_atom *atom,*btom;
+       int i,j,k,count;
+       t_atom *itom,*jtom,*ktom;
        t_linkcell *lc;
-       t_list *this,neighbour[27];
-       int i,j,c;
-       int count;
-       t_3dvec force,distance;
-       double d,u;
-       double sc,equi_dist;
-       int ni,nj,nk;
+       t_list neighbour_i[27];
+       t_list neighbour_i2[27];
+       //t_list neighbour_j[27];
+       t_list *this,*that;
+       u8 bc_ij,bc_ik;
+       int dnlc;
 
-       params=moldyn->pot_params;
-       atom=moldyn->atom;
-       lc=&(moldyn->lc);
-       sc=params->spring_constant;
-       equi_dist=params->equilibrium_distance;
        count=moldyn->count;
+       itom=moldyn->atom;
+       lc=&(moldyn->lc);
 
-       /* reset energy counter */
-       u=0.0;
+       /* reset energy */
+       moldyn->energy=0.0;
 
+       /* get energy and force of every atom */
        for(i=0;i<count;i++) {
+
                /* reset force */
-               v3_zero(&(atom[i].f));
-
-               /* determine cell + neighbours */
-               ni=(atom[i].r.x+(moldyn->dim.x/2))/lc->x;
-               nj=(atom[i].r.y+(moldyn->dim.y/2))/lc->y;
-               nk=(atom[i].r.z+(moldyn->dim.z/2))/lc->z;
-               c=link_cell_neighbour_index(moldyn,ni,nj,nk,neighbour);
-
-               /*
-                * processing cell of atom i
-                * => no need to check for empty list (1 element at minimum)
-                */
-               this=&(neighbour[0]);
-               list_reset(this);
-               do {
-                       btom=this->current->data;
-                       if(btom==&(atom[i]))
-                               continue;
-                       v3_sub(&distance,&(atom[i].r),&(btom->r));
-                       d=v3_norm(&distance);
-                       if(d<=moldyn->cutoff) {
-                               u+=(0.5*sc*(d-equi_dist)*(d-equi_dist));
-                               v3_scale(&force,&distance,
-                                        -sc*(1.0-(equi_dist/d)));
-                               v3_add(&(atom[i].f),&(atom[i].f),&force);
-                       }
-               } while(list_next(this)!=L_NO_NEXT_ELEMENT);
-
-               /*
-                * direct neighbour cells
-                * => no boundary condition check necessary
-                */
-               for(j=1;j<c;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this); /* there might not be a single atom */
-                       if(this->start!=NULL) {
-
-                       do {
-                               btom=this->current->data;
-                               v3_sub(&distance,&(atom[i].r),&(btom->r));
-                               d=v3_norm(&distance);
-                               if(d<=moldyn->cutoff) {
-                                       u+=(0.5*sc*(d-equi_dist)*(d-equi_dist));
-                                       v3_scale(&force,&distance,
-                                                -sc*(1.0-(equi_dist/d)));
-                                       v3_add(&(atom[i].f),&(atom[i].f),
-                                              &force);
-                               }
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+               v3_zero(&(itom[i].f));
 
-                       }
-               }
+               /* single particle potential/force */
+               if(itom[i].attr&ATOM_ATTR_1BP)
+                       moldyn->func1b(moldyn,&(itom[i]));
 
-               /*
-                * indirect neighbour cells
-                * => check boundary conditions
-                */
-               for(j=c;j<27;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this); /* check boundary conditions */
-                       if(this->start!=NULL) {
-
-                       do {
-                               btom=this->current->data;
-                               v3_sub(&distance,&(atom[i].r),&(btom->r));
-                               v3_per_bound(&distance,&(moldyn->dim));
-                               d=v3_norm(&distance);
-                               if(d<=moldyn->cutoff) {
-                                       u+=(0.5*sc*(d-equi_dist)*(d-equi_dist));
-                                       v3_scale(&force,&distance,
-                                                -sc*(1.0-(equi_dist/d)));
-                                       v3_add(&(atom[i].f),&(atom[i].f),
-                                              &force);
-                               }
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+               /* 2 body pair potential/force */
+               if(itom[i].attr&(ATOM_ATTR_2BP|ATOM_ATTR_3BP)) {
+       
+                       link_cell_neighbour_index(moldyn,
+                               (itom[i].r.x+moldyn->dim.x/2)/lc->x,
+                               (itom[i].r.y+moldyn->dim.y/2)/lc->y,
+                               (itom[i].r.z+moldyn->dim.z/2)/lc->z,
+                               neighbour_i);
 
-                       }
-               }
-       }
+                       dnlc=lc->dnlc;
 
-       moldyn->energy=0.5*u;
+                       for(j=0;j<27;j++) {
 
-       return 0;
-}
+                               this=&(neighbour_i[j]);
+                               list_reset(this);
 
-/* lennard jones potential & force for one sort of atoms */
-int lennard_jones(t_moldyn *moldyn) {
+                               if(this->start==NULL)
+                                       continue;
 
-       t_lj_params *params;
-       t_atom *atom,*btom;
-       t_linkcell *lc;
-       t_list *this,neighbour[27];
-       int i,j,c;
-       int count;
-       t_3dvec force,distance;
-       double d,h1,h2,u;
-       double eps,sig6,sig12;
-       int ni,nj,nk;
+                               bc_ij=(j<dnlc)?0:1;
 
-       params=moldyn->pot_params;
-       atom=moldyn->atom;
-       lc=&(moldyn->lc);
-       count=moldyn->count;
-       eps=params->epsilon4;
-       sig6=params->sigma6;
-       sig12=params->sigma12;
+                               do {
+                                       jtom=this->current->data;
+
+                                       if(jtom==&(itom[i]))
+                                               continue;
 
-       /* reset energy counter */
-       u=0.0;
+                                       if((jtom->attr&ATOM_ATTR_2BP)&
+                                          (itom[i].attr&ATOM_ATTR_2BP))
+                                               moldyn->func2b(moldyn,
+                                                              &(itom[i]),
+                                                              jtom,
+                                                              bc_ij);
 
-       for(i=0;i<count;i++) {
-               /* reset force */
-               v3_zero(&(atom[i].f));
-
-               /* determine cell + neighbours */
-               ni=(atom[i].r.x+(moldyn->dim.x/2))/lc->x;
-               nj=(atom[i].r.y+(moldyn->dim.y/2))/lc->y;
-               nk=(atom[i].r.z+(moldyn->dim.z/2))/lc->z;
-               c=link_cell_neighbour_index(moldyn,ni,nj,nk,neighbour);
-
-               /* processing cell of atom i */
-               this=&(neighbour[0]);
-               list_reset(this); /* list has 1 element at minimum */
-               do {
-                       btom=this->current->data;
-                       if(btom==&(atom[i]))
+                                       /* 3 body potential/force */
+
+                                       if(!(itom[i].attr&ATOM_ATTR_3BP)||
+                                          !(jtom->attr&ATOM_ATTR_3BP))
+                                               continue;
+
+                                       /* copy the neighbour lists */
+                                       memcpy(neighbour_i2,neighbour_i,
+                                              27*sizeof(t_list));
+
+                                       /* get neighbours of i */
+                                       for(k=0;k<27;k++) {
+
+                                               that=&(neighbour_i2[k]);
+                                               list_reset(that);
+                                       
+                                               if(that->start==NULL)
+                                                       continue;
+
+                                               bc_ik=(k<dnlc)?0:1;
+
+                                               do {
+
+                       ktom=that->current->data;
+
+                       if(!(ktom->attr&ATOM_ATTR_3BP))
+                               continue;
+
+                       if(ktom==jtom)
                                continue;
-                       v3_sub(&distance,&(atom[i].r),&(btom->r));
-                       d=v3_absolute_square(&distance);        /* 1/r^2 */
-                       if(d<=moldyn->cutoff_square) {
-                               d=1.0/d;        /* 1/r^2 */
-                               h2=d*d;         /* 1/r^4 */
-                               h2*=d;          /* 1/r^6 */
-                               h1=h2*h2;       /* 1/r^12 */
-                               u+=eps*(sig12*h1-sig6*h2);
-                               h2*=d;          /* 1/r^8 */
-                               h1*=d;          /* 1/r^14 */
-                               h2*=6*sig6;
-                               h1*=12*sig12;
-                               d=+h1-h2;
-                               d*=eps;
-                               v3_scale(&force,&distance,d);
-                               v3_add(&(atom[i].f),&(atom[i].f),&force);
-                       }
-               } while(list_next(this)!=L_NO_NEXT_ELEMENT);
-
-               /* neighbours not doing boundary condition overflow */
-               for(j=1;j<c;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this); /* there might not be a single atom */
-                       if(this->start!=NULL) {
-
-                       do {
-                               btom=this->current->data;
-                               v3_sub(&distance,&(atom[i].r),&(btom->r));
-                               d=v3_absolute_square(&distance); /* r^2 */
-                               if(d<=moldyn->cutoff_square) {
-                                       d=1.0/d;        /* 1/r^2 */
-                                       h2=d*d;         /* 1/r^4 */
-                                       h2*=d;          /* 1/r^6 */
-                                       h1=h2*h2;       /* 1/r^12 */
-                                       u+=eps*(sig12*h1-sig6*h2);
-                                       h2*=d;          /* 1/r^8 */
-                                       h1*=d;          /* 1/r^14 */
-                                       h2*=6*sig6;
-                                       h1*=12*sig12;
-                                       d=+h1-h2;
-                                       d*=eps;
-                                       v3_scale(&force,&distance,d);
-                                       v3_add(&(atom[i].f),&(atom[i].f),
-                                              &force);
-                               }
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
-                               
-                       }
-               }
 
-               /* neighbours due to boundary conditions */
-               for(j=c;j<27;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this); /* check boundary conditions */
-                       if(this->start!=NULL) {
-
-                       do {
-                               btom=this->current->data;
-                               v3_sub(&distance,&(atom[i].r),&(btom->r));
-                               v3_per_bound(&distance,&(moldyn->dim));
-                               d=v3_absolute_square(&distance); /* r^2 */
-                               if(d<=moldyn->cutoff_square) {
-                                       d=1.0/d;        /* 1/r^2 */
-                                       h2=d*d;         /* 1/r^4 */
-                                       h2*=d;          /* 1/r^6 */
-                                       h1=h2*h2;       /* 1/r^12 */
-                                       u+=eps*(sig12*h1-sig6*h2);
-                                       h2*=d;          /* 1/r^8 */
-                                       h1*=d;          /* 1/r^14 */
-                                       h2*=6*sig6;
-                                       h1*=12*sig12;
-                                       d=+h1-h2;
-                                       d*=eps;
-                                       v3_scale(&force,&distance,d);
-                                       v3_add(&(atom[i].f),&(atom[i].f),
-                                              &force);
+                       if(ktom==&(itom[i]))
+                               continue;
+
+                       moldyn->func3b(moldyn,&(itom[i]),jtom,ktom,bc_ik|bc_ij);
+
+                                               } while(list_next(that)!=\
+                                                       L_NO_NEXT_ELEMENT);
+
+                                       }
+                                       
+                               } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+               
+                               /* 2bp post function */
+                               if(moldyn->func2b_post) {
+printf("pre(%d): %.15f %.15f %.15f\n",i,itom[i].f.x,itom[i].r.x,itom[i].v.x);
+                                       moldyn->func2b_post(moldyn,
+                                                           &(itom[i]),
+                                                           jtom,bc_ij);
+printf("post(%d): %.15f %.15f %.15f\n",i,itom[i].f.x,itom[i].r.x,itom[i].v.x);
                                }
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
 
                        }
                }
        }
 
-       moldyn->energy=0.5*u;
+       return 0;
+}
+
+/*
+ * periodic boundayr checking
+ */
+
+int check_per_bound(t_moldyn *moldyn,t_3dvec *a) {
        
+       double x,y,z;
+       t_3dvec *dim;
+
+       dim=&(moldyn->dim);
+
+       x=0.5*dim->x;
+       y=0.5*dim->y;
+       z=0.5*dim->z;
+
+       if(moldyn->status&MOLDYN_STAT_PBX) {
+               if(a->x>=x) a->x-=dim->x;
+               else if(-a->x>x) a->x+=dim->x;
+       }
+       if(moldyn->status&MOLDYN_STAT_PBY) {
+               if(a->y>=y) a->y-=dim->y;
+               else if(-a->y>y) a->y+=dim->y;
+       }
+       if(moldyn->status&MOLDYN_STAT_PBZ) {
+               if(a->z>=z) a->z-=dim->z;
+               else if(-a->z>z) a->z+=dim->z;
+       }
+
        return 0;
 }
+        
 
-/* tersoff potential & force for 2 sorts of atoms */
+/*
+ * example potentials
+ */
 
-int tersoff(t_moldyn *moldyn) {
+/* harmonic oscillator potential and force */
 
-       t_tersoff_params *params;
-       t_atom *atom,*btom,*ktom;
-       t_linkcell *lc;
-       t_list *this,*thisk,neighbour[27],neighbourk[27];
-       int i,j,k,c,ck;
-       int count;
-       double u;
-       int ni,nj,nk;
-       int ki,kj,kk;
-       
+int harmonic_oscillator(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
 
-       params=moldyn->pot_params;
-       atom=moldyn->atom;
-       lc=&(moldyn->lc);
-       count=moldyn->count;
+       t_ho_params *params;
+       t_3dvec force,distance;
+       double d;
+       double sc,equi_dist;
+
+       params=moldyn->pot2b_params;
+       sc=params->spring_constant;
+       equi_dist=params->equilibrium_distance;
+
+       v3_sub(&distance,&(ai->r),&(aj->r));
        
-       /* reset energy counter */
-       u=0.0;
+       if(bc) check_per_bound(moldyn,&distance);
+       d=v3_norm(&distance);
+       if(d<=moldyn->cutoff) {
+               /* energy is 1/2 (d-d0)^2, but we will add this twice ... */
+               moldyn->energy+=(0.25*sc*(d-equi_dist)*(d-equi_dist));
+               v3_scale(&force,&distance,-sc*(1.0-(equi_dist/d)));
+               v3_add(&(ai->f),&(ai->f),&force);
+       }
 
-       for(i=0;i<count;i++) {
-               /* reset force */
-               v3_zero(&(atom[i].f));
-
-               /* determin cell neighbours */
-               ni=(atom[i].r.x+(moldyn->dim.x/2))/lc->x;
-               nj=(atom[i].r.y+(moldyn->dim.y/2))/lc->y;
-               nk=(atom[i].r.z+(moldyn->dim.z/2))/lc->z;
-               c=link_cell_neighbour_index(moldyn,ni,nj,nk,neighbour);
-
-               /*
-                * processing cell of atom i
-                * => no need to check for empty list (1 element at minimum)
-                */
-               this=&(neighbour[0]);
-               list_reset(this);
-               do {
-                       btom=this->current->data;
-                       if(btom==&(atom[i]))
-                               continue;
+       return 0;
+}
 
-                       /* 2 body stuff */
-
-                       v3_sub(&dist_ij,btom,&(atom[i]));
-                       d_ij=v3_norm(&dist_ij);
-                       if(d_ij<=S) {
-
-                               S=;
-                               R=;
-                               A=;
-                               lambda=;
-                               B=;
-                               mu=;
-                               chi=;
-                               beta=;
-                               betaN=;
-
-                               if(d_ij<=R) {
-                                       f_c=1.0;
-                                       df_c=0.0;
-                               }
-                               else {
-                                       s_r=S-R;
-                                       arg1=PI*(d_ij-R)/s_r;
-                                       f_c=0.5+0.5*cos(arg1);
-                                       df_c=-0.5*sin(arg1)*(PI/(s_r*d_ij));
-                                       f_r=A*exp(-lambda*d_ij);
-                                       f_a=-B*exp(-mu*d_ij);
-                               }
-                       }
-                       else 
-                               continue;               
-
-                       
-                       /* end 2 body stuff */ 
-
-                       /* determine cell neighbours of btom */
-                       ki=(btom->r.x+(moldyn->dim.x/2))/lc->x;
-                       kj=(btom->r.y+(moldyn->dim.y/2))/lc->y;
-                       kk=(btom->r.z+(moldyn->dim.z/2))/lc->z;
-                       ck=link_cell_neighbour_index(moldyn,ki,kj,kk,
-                                                    neighbourk);
-
-                       /* go for zeta - 3 body stuff! */
-                       zeta=0.0;
-                       d_ij2=d_ij*d_ij;
-
-                       /* cell of btom */
-                       thisk=&(neighbourk[0]);
-                       list_reset(thisk);
-                       do {
-                               ktom=thisk->current->data;
-                               if(ktom==btom)
-                                       continue;
-                               if(ktom==&(atom[i]))
-                                       continue;
-                               
-                               /* 3 body stuff (1) */
-                               
-                               v3_sub(&dist_ik,ktom,&(atom[i]));
-                               d_ik=v3_norm(&dist_ik);
-                               if(d_ik<=Sik) {
-
-                               Rik=;
-                               Sik=;
-                               Aik=;
-                               lambda_ik=;
-                               Bik=;
-                               mu_ik=;
-                               omega_ik=;
-                               c_i=;
-                               d_i=;
-                               h_i=;
-                       
-
-                                       if(d_ik<=Rik) {
-                                               f_cik=1.0;
-                                               df_cik=0.0;
-                                       }
-                                       else {
-                                               sik_rik=Sik-Rik;
-                                               arg1ik=PI*(d_ik-Rik)/sik_rik;
-                                               f_cik=0.5+0.5*cos(arg1ik);
-                                               df_cik=-0.5*sin(arg1ik)* \
-                                                      (PI/(sik_rik*d_ik));
-                                               f_rik=Aik*exp(-lambda_ik*d_ik);
-                                               f_aik=-Bik*exp(-mu_ik*d_ik);
-                                       }
-                       
-                                       v3_sub(&distance_jk,ktom,btom);
-                                       cos_theta=(d_ij2+d_ik*d_ik-d_jk*d_jk)/\
-                                                 (2*d_ij*d_ik);
-                                       theta=arccos(cos_theta);
+/* lennard jones potential & force for one sort of atoms */
+int lennard_jones(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
 
-                                       
-                               }
-                               else
-                                       continue;
+       t_lj_params *params;
+       t_3dvec force,distance;
+       double d,h1,h2;
+       double eps,sig6,sig12;
 
-                               /* end 3 body stuff (1) */
+       params=moldyn->pot2b_params;
+       eps=params->epsilon4;
+       sig6=params->sigma6;
+       sig12=params->sigma12;
 
+       v3_sub(&distance,&(ai->r),&(aj->r));
+       if(bc) check_per_bound(moldyn,&distance);
+       d=v3_absolute_square(&distance);        /* 1/r^2 */
+       if(d<=moldyn->cutoff_square) {
+               d=1.0/d;                        /* 1/r^2 */
+               h2=d*d;                         /* 1/r^4 */
+               h2*=d;                          /* 1/r^6 */
+               h1=h2*h2;                       /* 1/r^12 */
+               /* energy is eps*..., but we will add this twice ... */
+               moldyn->energy+=0.5*eps*(sig12*h1-sig6*h2);
+               h2*=d;                          /* 1/r^8 */
+               h1*=d;                          /* 1/r^14 */
+               h2*=6*sig6;
+               h1*=12*sig12;
+               d=+h1-h2;
+               d*=eps;
+               v3_scale(&force,&distance,d);
+               v3_add(&(ai->f),&(ai->f),&force);
+       }
 
-                       } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       return 0;
+}
 
-                       /* direct neighbours of btom cell */
-                       for(k=1;k<ck;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+/*
+ * tersoff potential & force for 2 sorts of atoms
+ */
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+/* create mixed terms from parameters and set them */
+int tersoff_mult_complete_params(t_tersoff_mult_params *p) {
+
+       printf("[moldyn] tersoff parameter completion\n");
+       p->Smixed=sqrt(p->S[0]*p->S[1]);
+       p->Rmixed=sqrt(p->R[0]*p->R[1]);
+       p->Amixed=sqrt(p->A[0]*p->A[1]);
+       p->Bmixed=sqrt(p->B[0]*p->B[1]);
+       p->lambda_m=0.5*(p->lambda[0]+p->lambda[1]);
+       p->mu_m=0.5*(p->mu[0]+p->mu[1]);
+
+       printf("[moldyn] tersoff mult parameter info:\n");
+       printf("  S (m)  | %.12f | %.12f | %.12f\n",p->S[0],p->S[1],p->Smixed);
+       printf("  R (m)  | %.12f | %.12f | %.12f\n",p->R[0],p->R[1],p->Rmixed);
+       printf("  A (eV) | %f | %f | %f\n",p->A[0]/EV,p->A[1]/EV,p->Amixed/EV);
+       printf("  B (eV) | %f | %f | %f\n",p->B[0]/EV,p->B[1]/EV,p->Bmixed/EV);
+       printf("  lambda | %f | %f | %f\n",p->lambda[0],p->lambda[1],
+                                         p->lambda_m);
+       printf("  mu     | %f | %f | %f\n",p->mu[0],p->mu[1],p->mu_m);
+       printf("  beta   | %.10f | %.10f\n",p->beta[0],p->beta[1]);
+       printf("  n      | %f | %f\n",p->n[0],p->n[1]);
+       printf("  c      | %f | %f\n",p->c[0],p->c[1]);
+       printf("  d      | %f | %f\n",p->d[0],p->d[1]);
+       printf("  h      | %f | %f\n",p->h[0],p->h[1]);
+       printf("  chi    | %f \n",p->chi);
 
-                               /* 3 body stuff (2) */
+       return 0;
+}
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+/* tersoff 1 body part */
+int tersoff_mult_1bp(t_moldyn *moldyn,t_atom *ai) {
 
-                               }
-                       }
+       int num;
+       t_tersoff_mult_params *params;
+       t_tersoff_exchange *exchange;
+       
+       num=ai->bnum;
+       params=moldyn->pot1b_params;
+       exchange=&(params->exchange);
 
-                       /* indirect neighbours of btom cell */
-                       for(k=ck;k<27;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+       /*
+        * simple: point constant parameters only depending on atom i to
+        *         their right values
+        */
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+       exchange->beta=&(params->beta[num]);
+       exchange->n=&(params->n[num]);
+       exchange->c=&(params->c[num]);
+       exchange->d=&(params->d[num]);
+       exchange->h=&(params->h[num]);
 
-                               /* 3 body stuff */
+       exchange->betan=pow(*(exchange->beta),*(exchange->n));
+       exchange->n_betan=*(exchange->n)*exchange->betan;
+       exchange->c2=params->c[num]*params->c[num];
+       exchange->d2=params->d[num]*params->d[num];
+       exchange->c2d2=exchange->c2/exchange->d2;
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       return 0;
+}
+       
+/* tersoff 2 body part */
+int tersoff_mult_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
+
+       t_tersoff_mult_params *params;
+       t_tersoff_exchange *exchange;
+       t_3dvec dist_ij,force;
+       double d_ij;
+       double A,B,R,S,lambda,mu;
+       double f_r,df_r;
+       double f_c,df_c;
+       int num;
+       double s_r;
+       double arg;
+       double scale;
+
+       params=moldyn->pot2b_params;
+       num=ai->bnum;
+       exchange=&(params->exchange);
+
+       exchange->run3bp=0;
+       exchange->run2bp_post=0;
+       
+       /*
+        * we need: f_c, df_c, f_r, df_r
+        *
+        * therefore we need: R, S, A, lambda
+        */
 
-                               }
-                       }
+       v3_sub(&dist_ij,&(ai->r),&(aj->r));
 
+       if(bc) check_per_bound(moldyn,&dist_ij);
 
-               } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+       d_ij=v3_norm(&dist_ij);
 
-               /*
-                * direct neighbour cells of atom i
-                */
-               for(j=1;j<c;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this);
-                       if(this->start!=NULL) {
+       /* save for use in 3bp */
+       exchange->d_ij=d_ij;
+       exchange->dist_ij=dist_ij;
+       exchange->d_ij2=d_ij*d_ij;
 
-                       do {
-                               btom=this->current->data;
+       /* constants */
+       if(num==aj->bnum) {
+               S=params->S[num];
+               R=params->R[num];
+               A=params->A[num];
+               B=params->B[num];
+               lambda=params->lambda[num];
+               mu=params->mu[num];
+               params->exchange.chi=1.0;
+       }
+       else {
+               S=params->Smixed;
+               R=params->Rmixed;
+               A=params->Amixed;
+               B=params->Bmixed;
+               lambda=params->lambda_m;
+               mu=params->mu_m;
+               params->exchange.chi=params->chi;
+       }
+       if(d_ij>S)
+               return 0;
 
-                               /* 2 body stuff */
+       f_r=A*exp(-lambda*d_ij);
+       df_r=-lambda*f_r/d_ij;
 
+       /* f_a, df_a calc + save for later use */
+       exchange->f_a=-B*exp(-mu*d_ij);
+       exchange->df_a=-mu*exchange->f_a/d_ij;
 
-                       /* determine cell neighbours of btom */
-                       ki=(btom->r.x+(moldyn->dim.x/2))/lc->x;
-                       kj=(btom->r.y+(moldyn->dim.y/2))/lc->y;
-                       kk=(btom->r.z+(moldyn->dim.z/2))/lc->z;
-                       ck=link_cell_neighbour_index(moldyn,ki,kj,kk,
-                                                    neighbourk);
+       if(d_ij<R) {
+               /* f_c = 1, df_c = 0 */
+               f_c=1.0;
+               df_c=0.0;
+               v3_scale(&force,&dist_ij,df_r);
+       }
+       else {
+               s_r=S-R;
+               arg=M_PI*(d_ij-R)/s_r;
+               f_c=0.5+0.5*cos(arg);
+               df_c=-0.5*sin(arg)*(M_PI/(s_r*d_ij));
+               scale=df_c*f_r+df_r*f_c;
+               v3_scale(&force,&dist_ij,scale);
+       }
 
-                       /* cell of btom */
-                       thisk=&(neighbourk[0]);
-                       list_reset(thisk);
-                       do {
-                               ktom=thisk->current->data;
-                               if(ktom==btom)
-                                       continue;
-                               if(ktom==&(atom[i]))
-                                       continue;
-                               
-                               /* 3 body stuff (1) */
+       /* add forces */
+       v3_add(&(ai->f),&(ai->f),&force);
+       /* energy is 0.5 f_r f_c ... */
+       moldyn->energy+=(0.5*f_r*f_c);
 
-                       } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       /* save for use in 3bp */
+       exchange->f_c=f_c;
+       exchange->df_c=df_c;
 
-                       /* direct neighbours of btom cell */
-                       for(k=1;k<ck;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+       /* enable the run of 3bp function and 2bp post processing */
+       exchange->run3bp=1;
+       exchange->run2bp_post=1;
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+       /* reset 3bp sums */
+       exchange->sum1_3bp=0.0;
+       exchange->sum2_3bp=0.0;
+       v3_zero(&(exchange->db_ij));
 
-                               /* 3 body stuff (2) */
+       return 0;
+}
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+/* tersoff 2 body post part */
 
-                               }
-                       }
+int tersoff_mult_post_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
 
-                       /* indirect neighbours of btom cell */
-                       for(k=ck;k<27;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+       /* here we have to allow for the 3bp sums */
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+       t_tersoff_mult_params *params;
+       t_tersoff_exchange *exchange;
 
-                               /* 3 body stuff (3) */
+       t_3dvec force,temp,*db_ij,*dist_ij;
+       double db_ij_scale1,db_ij_scale2;
+       double b_ij;
+       double f_c,df_c,f_a,df_a;
+       double chi,betan;
+       double help;
+       double n;
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       params=moldyn->pot2b_params;
+       exchange=&(params->exchange);
 
-                               }
-                       }
+       /* we do not run if f_c_ij was detected to be 0! */
+       if(!(exchange->run2bp_post))
+               return 0;
 
+       db_ij=&(exchange->db_ij);
+       f_c=exchange->f_c;
+       df_c=exchange->df_c;
+       f_a=exchange->f_a;
+       df_a=exchange->df_a;
+       betan=exchange->betan;
+       n=*(exchange->n);
+       chi=exchange->chi;
+       dist_ij=&(exchange->dist_ij);
 
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+       db_ij_scale1=(1+betan*exchange->sum1_3bp);
+       db_ij_scale2=(exchange->n_betan*exchange->sum2_3bp);
+       help=pow(db_ij_scale1,-1.0/(2*n)-1);
+       b_ij=chi*db_ij_scale1*help;
+       db_ij_scale1=-chi/(2*n)*help;
+printf("debug: %.20f %.20f %.20f\n",db_ij->x,exchange->sum1_3bp,exchange->sum2_3bp);
 
-                       }
-               }
+       /* db_ij part */
+       v3_scale(db_ij,db_ij,(db_ij_scale1*db_ij_scale2));
+       v3_scale(db_ij,db_ij,f_a);
 
-               /*
-                * indirect neighbour cells of atom i
-                */
-               for(j=c;j<27;j++) {
-                       this=&(neighbour[j]);
-                       list_reset(this);
-                       if(this->start!=NULL) {
-
-                       do {
-                               btom=this->current->data;
-
-                               /* 2 body stuff */
-
-
-                       /* determine cell neighbours of btom */
-                       ki=(btom->r.x+(moldyn->dim.x/2))/lc->x;
-                       kj=(btom->r.y+(moldyn->dim.y/2))/lc->y;
-                       kk=(btom->r.z+(moldyn->dim.z/2))/lc->z;
-                       ck=link_cell_neighbour_index(moldyn,ki,kj,kk,
-                                                    neighbourk);
-
-                       /* cell of btom */
-                       thisk=&(neighbourk[0]);
-                       list_reset(thisk);
-                       do {
-                               ktom=thisk->current->data;
-                               if(ktom==btom)
-                                       continue;
-                               if(ktom==&(atom[i]))
-                                       continue;
-                               
-                               /* 3 body stuff (1) */
+       /* df_a part */
+       v3_scale(&temp,dist_ij,b_ij*df_a);
 
-                       } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       /* db_ij + df_a part */
+       v3_add(&force,&temp,db_ij);
+       v3_scale(&force,&force,f_c);
 
-                       /* direct neighbours of btom cell */
-                       for(k=1;k<ck;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+       /* df_c part */
+       v3_scale(&temp,dist_ij,f_a*b_ij*df_c);
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+       /* add energy of 3bp sum */
+       moldyn->energy+=(0.5*f_c*b_ij*f_a);
 
-                               /* 3 body stuff (2) */
+       /* add force of 3bp calculation (all three parts) */
+       v3_add(&(ai->f),&temp,&force);
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       return 0;
+}
 
-                               }
-                       }
+/* tersoff 3 body part */
+
+int tersoff_mult_3bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,t_atom *ak,u8 bc) {
+
+       t_tersoff_mult_params *params;
+       t_tersoff_exchange *exchange;
+       t_3dvec dist_ij,dist_ik,dist_jk;
+       t_3dvec temp,force;
+       double R,S,s_r;
+       double d_ij,d_ij2,d_ik,d_jk;
+       double f_c,df_c,f_a,df_a;
+       double f_c_ik,df_c_ik,arg;
+       double n,c,d,h;
+       double c2,d2,c2d2;
+       double numer,denom;
+       double theta,cos_theta,sin_theta;
+       double d_theta,d_theta1,d_theta2;
+       double h_cos,d2_h_cos2;
+       double frac,bracket,bracket_n_1,bracket_n;
+       double g;
+       int num;
+
+       params=moldyn->pot3b_params;
+       num=ai->bnum;
+       exchange=&(params->exchange);
+
+       if(!(exchange->run3bp))
+               return 0;
+
+       /*
+        * we need: f_c, d_fc, b_ij, db_ij, f_a, df_a
+        *
+        * we got f_c, df_c, f_a, df_a from 2bp calculation
+        */
 
-                       /* indirect neighbours of btom cell */
-                       for(k=ck;k<27;k++) {
-                               thisk=&(neighbourk[k]);
-                               list_reset(thisk);
-                               if(thisk->start!=NULL) {
+       d_ij=exchange->d_ij;
+       d_ij2=exchange->d_ij2;
+       dist_ij=exchange->dist_ij;
 
-                               do {
-                                       ktom=thisk->current->data;
-                                       if(ktom==&(atom[i]))
-                                               continue;
+       f_a=params->exchange.f_a;
+       df_a=params->exchange.df_a;
 
-                               /* 3 body stuff (3) */
+       f_c=exchange->f_c;
+       df_c=exchange->df_c;
+       
+       /* d_ij is <= S, as we didn't return so far! */
 
-                               } while(list_next(thisk)!=L_NO_NEXT_ELEMENT);
+       /*
+        * calc of b_ij (scalar) and db_ij (vector)
+        *
+        * - for b_ij: chi, beta, f_c_ik, w(=1), c, d, h, n, cos_theta
+        *
+        * - for db_ij: d_theta, sin_theta, cos_theta, f_c_ik, df_c_ik,
+        *              w_ik,
+        *
+        */
 
-                               }
-                       }
+       v3_sub(&dist_ik,&(ai->r),&(ak->r));
+       if(bc) check_per_bound(moldyn,&dist_ik);
+       d_ik=v3_norm(&dist_ik);
 
+       /* constants for f_c_ik calc */
+       if(num==ak->bnum) {
+               R=params->R[num];
+               S=params->S[num];
+       }
+       else {
+               R=params->Rmixed;
+               S=params->Smixed;
+       }
 
-                       } while(list_next(this)!=L_NO_NEXT_ELEMENT);
+       /* calc of f_c_ik */
+       if(d_ik>S) {
+               f_c_ik=0.0;
+               df_c_ik=0.0;
+       }
+       else if(d_ik<R) {
+               f_c_ik=1.0;
+               df_c_ik=0.0;
+       }
+       else {
+               s_r=S-R;
+               arg=M_PI*(d_ik-R)/s_r;
+               f_c_ik=0.5+0.5*cos(arg);
+               df_c_ik=-0.5*sin(arg)*(M_PI/(s_r*d_ik));
+       }
+       
+       v3_sub(&dist_jk,&(aj->r),&(ak->r));
+       if(bc) check_per_bound(moldyn,&dist_jk);
+       d_jk=v3_norm(&dist_jk);
+
+       /* get exchange data */
+       n=*(exchange->n);
+       c=*(exchange->c);
+       d=*(exchange->d);
+       h=*(exchange->h);
+       c2=exchange->c2;
+       d2=exchange->d2;
+       c2d2=exchange->c2d2;
+
+       /* cosine of theta by scalaproduct,       *
+        * derivation of theta by law of cosines! */
+       numer=d_ij2+d_ik*d_ik-d_jk*d_jk;
+       denom=2*d_ij*d_ik;
+       cos_theta=numer/denom;
+       cos_theta=v3_scalar_product(&dist_ij,&dist_ik)/(d_ij*d_ik);
+printf("cos theta: %.25f\n",cos_theta);
+
+       /* hack - cos theta machine accuracy problems! */
+       if(cos_theta>1.0||cos_theta<-1.0) {
+               moldyn->debug++;
+               if(fabs(cos_theta)>1.0+ACCEPTABLE_ERROR)
+                       printf("[moldyn] WARNING: cos theta failure!\n");
+               if(cos_theta<0)
+                       cos_theta=-1.0;
+               else
+                       cos_theta=1.0;
+               printf("THETA CORRECTION\n");
+       }
 
-                       }
-               }
-               
+       sin_theta=sqrt(1.0-(cos_theta*cos_theta));
+       theta=acos(cos_theta);
+       d_theta=(-1.0/sqrt(1.0-cos_theta*cos_theta))/(denom*denom);
+       d_theta1=2*denom-numer*2*d_ik/d_ij;
+       d_theta2=2*denom-numer*2*d_ij/d_ik;
+       d_theta1*=d_theta;
+       d_theta2*=d_theta;
+printf("FOO %.15f %.15f\n",sin_theta,cos_theta);
+
+       h_cos=(h-cos_theta);
+       d2_h_cos2=d2+(h_cos*h_cos);
+
+       frac=c2/(d2_h_cos2);
+       g=1.0+c2d2-frac;
+
+       if(f_c_ik==0.0) {
+               bracket=0.0;
+               bracket_n_1=0.0;
+               bracket_n=0.0;
        }
+       else {
+               bracket=f_c_ik*g;
+               bracket_n_1=pow(bracket,n-1.0);
+               bracket_n=bracket_n_1*bracket;
+       }
+
+       /* calc of db_ij and the 2 sums */
+       exchange->sum1_3bp+=bracket_n;
+       exchange->sum2_3bp+=bracket_n_1;
+
+       /* derivation of theta */
+       v3_scale(&force,&dist_ij,d_theta1);
+       v3_scale(&temp,&dist_ik,d_theta2);
+       v3_add(&force,&force,&temp);
 
-       moldyn->energy=0.5*u;
+printf("DA:%.20f %.20f %.20f\n",d_theta1,force.x,temp.x);
+       /* part 1 of db_ij */
+       v3_scale(&force,&force,sin_theta*2*h_cos*f_c_ik*frac/d2_h_cos2);
 
+       /* part 2 of db_ij */
+       v3_scale(&temp,&dist_ik,df_c_ik*g);
+
+       /* sum up and add to db_ij */
+       v3_add(&temp,&temp,&force);
+       v3_add(&(exchange->db_ij),&(exchange->db_ij),&temp);
+                               
        return 0;
 }