extended debugging, implemented fixed position attribute
[physik/posic.git] / moldyn.c
index 3c4d873..80cf572 100644 (file)
--- a/moldyn.c
+++ b/moldyn.c
@@ -126,6 +126,18 @@ int set_cutoff(t_moldyn *moldyn,double cutoff) {
        return 0;
 }
 
+int set_bondlen(t_moldyn *moldyn,double b0,double b1,double bm) {
+
+       moldyn->bondlen[0]=b0*b0;
+       moldyn->bondlen[1]=b1*b1;
+       if(bm<0)
+               moldyn->bondlen[2]=b0*b1;
+       else
+               moldyn->bondlen[2]=bm*bm;
+
+       return 0;
+}
+
 int set_temperature(t_moldyn *moldyn,double t_ref) {
 
        moldyn->t_ref=t_ref;
@@ -364,7 +376,7 @@ int moldyn_set_log(t_moldyn *moldyn,u8 type,int timer) {
                        break;
                case VISUAL_STEP:
                        moldyn->vwrite=timer;
-                       ret=visual_init(&(moldyn->vis),moldyn->vlsdir);
+                       ret=visual_init(moldyn,moldyn->vlsdir);
                        if(ret<0) {
                                printf("[moldyn] visual init failure\n");
                                return ret;
@@ -583,7 +595,7 @@ int add_atom(t_moldyn *moldyn,int element,double mass,u8 brand,u8 attr,
        int count;
        
        atom=moldyn->atom;
-       count=(moldyn->count)++;
+       count=(moldyn->count)++;        // asshole style!
 
        ptr=realloc(atom,(count+1)*sizeof(t_atom));
        if(!ptr) {
@@ -593,6 +605,9 @@ int add_atom(t_moldyn *moldyn,int element,double mass,u8 brand,u8 attr,
        moldyn->atom=ptr;
 
        atom=moldyn->atom;
+
+       /* initialize new atom */
+       memset(&(atom[count]),0,sizeof(t_atom));
        atom[count].r=*r;
        atom[count].v=*v;
        atom[count].element=element;
@@ -942,12 +957,43 @@ double pressure_calc(t_moldyn *moldyn) {
        return moldyn->p;
 }
 
+int average_reset(t_moldyn *moldyn) {
+
+       printf("[moldyn] average reset\n");
+
+       /* update skip value */
+       moldyn->avg_skip=moldyn->total_steps;
+
+       /* kinetic energy */
+       moldyn->k_sum=0.0;
+       moldyn->k2_sum=0.0;
+       
+       /* potential energy */
+       moldyn->v_sum=0.0;
+       moldyn->v2_sum=0.0;
+
+       /* temperature */
+       moldyn->t_sum=0.0;
+
+       /* virial */
+       moldyn->virial_sum=0.0;
+       moldyn->gv_sum=0.0;
+
+       /* pressure */
+       moldyn->p_sum=0.0;
+       moldyn->gp_sum=0.0;
+
+       return 0;
+}
+
 int average_and_fluctuation_calc(t_moldyn *moldyn) {
 
+       int denom;
+
        if(moldyn->total_steps<moldyn->avg_skip)
                return 0;
 
-       int denom=moldyn->total_steps+1-moldyn->avg_skip;
+       denom=moldyn->total_steps+1-moldyn->avg_skip;
 
        /* assume up to date energies, temperature, pressure etc */
 
@@ -1019,7 +1065,8 @@ printf("  --> <dV2> sim: %f experimental: %f\n",moldyn->dv2_avg,1.5*moldyn->coun
 
 double thermodynamic_pressure_calc(t_moldyn *moldyn) {
 
-       t_3dvec dim,*tp;
+       t_3dvec dim;
+       //t_3dvec *tp;
        double u_up,u_down,dv;
        double scale,p;
        t_atom *store;
@@ -1246,25 +1293,57 @@ int link_cell_init(t_moldyn *moldyn,u8 vol) {
        lc->y=moldyn->dim.y/lc->ny;
        lc->nz=moldyn->dim.z/moldyn->cutoff;
        lc->z=moldyn->dim.z/lc->nz;
-
        lc->cells=lc->nx*lc->ny*lc->nz;
+
+#ifdef STATIC_LISTS
+       lc->subcell=malloc(lc->cells*sizeof(int*));
+#else
        lc->subcell=malloc(lc->cells*sizeof(t_list));
+#endif
+
+       if(lc->subcell==NULL) {
+               perror("[moldyn] cell init (malloc)");
+               return -1;
+       }
 
        if(lc->cells<27)
                printf("[moldyn] FATAL: less then 27 subcells!\n");
 
        if(vol) {
-               printf("[moldyn] initializing linked cells (%d)\n",lc->cells);
+#ifdef STATIC_LISTS
+               printf("[moldyn] initializing 'static' linked cells (%d)\n",
+                      lc->cells);
+#else
+               printf("[moldyn] initializing 'dynamic' linked cells (%d)\n",
+                      lc->cells);
+#endif
                printf("  x: %d x %f A\n",lc->nx,lc->x);
                printf("  y: %d x %f A\n",lc->ny,lc->y);
                printf("  z: %d x %f A\n",lc->nz,lc->z);
        }
 
+#ifdef STATIC_LISTS
+       /* list init */
+       for(i=0;i<lc->cells;i++) {
+               lc->subcell[i]=malloc((MAX_ATOMS_PER_LIST+1)*sizeof(int));
+               if(lc->subcell[i]==NULL) {
+                       perror("[moldyn] list init (malloc)");
+                       return -1;
+               }
+               /*
+               if(i==0)
+                       printf(" ---> %d malloc %p (%p)\n",
+                              i,lc->subcell[0],lc->subcell);
+               */
+       }
+#else
        for(i=0;i<lc->cells;i++)
                list_init_f(&(lc->subcell[i]));
+#endif
+
+       /* update the list */
+       link_cell_update(moldyn);
 
-       link_cell_update(moldyn);
-       
        return 0;
 }
 
@@ -1274,7 +1353,9 @@ int link_cell_update(t_moldyn *moldyn) {
        int nx,ny;
        t_atom *atom;
        t_linkcell *lc;
-       double x,y,z;
+#ifdef STATIC_LISTS
+       int p;
+#endif
 
        atom=moldyn->atom;
        lc=&(moldyn->lc);
@@ -1282,25 +1363,50 @@ int link_cell_update(t_moldyn *moldyn) {
        nx=lc->nx;
        ny=lc->ny;
 
-       x=moldyn->dim.x/2;
-       y=moldyn->dim.y/2;
-       z=moldyn->dim.z/2;
-
        for(i=0;i<lc->cells;i++)
+#ifdef STATIC_LISTS
+               memset(lc->subcell[i],0,(MAX_ATOMS_PER_LIST+1)*sizeof(int));
+#else
                list_destroy_f(&(lc->subcell[i]));
-       
+#endif
+
        for(count=0;count<moldyn->count;count++) {
                i=((atom[count].r.x+(moldyn->dim.x/2))/lc->x);
                j=((atom[count].r.y+(moldyn->dim.y/2))/lc->y);
                k=((atom[count].r.z+(moldyn->dim.z/2))/lc->z);
+       
+#ifdef STATIC_LISTS
+               p=0;
+               while(lc->subcell[i+j*nx+k*nx*ny][p]!=0)
+                       p++;
+
+               if(p>=MAX_ATOMS_PER_LIST) {
+                       printf("[moldyn] FATAL: amount of atoms too high!\n");
+                       return -1;
+               }
+
+               lc->subcell[i+j*nx+k*nx*ny][p]=count;
+#else
                list_add_immediate_f(&(lc->subcell[i+j*nx+k*nx*ny]),
                                     &(atom[count]));
+               /*
+               if(j==0&&k==0)
+                       printf(" ---> %d %d malloc %p (%p)\n",
+                              i,count,lc->subcell[i].current,lc->subcell);
+               */
+#endif
        }
 
        return 0;
 }
 
-int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
+int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,
+#ifdef STATIC_LISTS
+                              int **cell
+#else
+                              t_list *cell
+#endif
+                            ) {
 
        t_linkcell *lc;
        int a;
@@ -1318,6 +1424,10 @@ int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
        count2=27;
        a=nx*ny;
 
+       if(i>=nx||j>=ny||k>=nz)
+               printf("[moldyn] WARNING: lcni %d/%d %d/%d %d/%d\n",
+                      i,nx,j,ny,k,nz);
+
        cell[0]=lc->subcell[i+j*nx+k*a];
        for(ci=-1;ci<=1;ci++) {
                bx=0;
@@ -1363,8 +1473,14 @@ int link_cell_shutdown(t_moldyn *moldyn) {
 
        lc=&(moldyn->lc);
 
-       for(i=0;i<lc->nx*lc->ny*lc->nz;i++)
-               list_destroy_f(&(moldyn->lc.subcell[i]));
+       for(i=0;i<lc->cells;i++) {
+#ifdef STATIC_LISTS
+               free(lc->subcell[i]);
+#else
+               //printf(" ---> %d free %p\n",i,lc->subcell[i].start);
+               list_destroy_f(&(lc->subcell[i]));
+#endif
+       }
 
        free(lc->subcell);
 
@@ -1457,19 +1573,19 @@ int moldyn_integrate(t_moldyn *moldyn) {
        /* calculate initial forces */
        potential_force_calc(moldyn);
 #ifdef DEBUG
-return 0;
+//return 0;
 #endif
 
        /* 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");
+               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");
+               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");
+               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");
+               printf("[moldyn] WARNING: forces too high / tau too small!\n");
 
        /* zero absolute time */
        moldyn->time=0.0;
@@ -1563,27 +1679,27 @@ return 0;
                }
                if(v) {
                        if(!(moldyn->total_steps%v)) {
-                               visual_atoms(&(moldyn->vis),moldyn->time,
-                                            moldyn->atom,moldyn->count);
+                               visual_atoms(moldyn);
                        }
                }
 
                /* display progress */
-               if(!(moldyn->total_steps%10)) {
+               //if(!(moldyn->total_steps%10)) {
                        /* get current time */
                        gettimeofday(&t2,NULL);
 
-       printf("\rsched:%d, steps:%d, T:%3.1f/%3.1f P:%4.1f/%4.1f V:%6.1f (%d)",
-              sched->count,i,
-              moldyn->t,moldyn->t_avg,
-              moldyn->p_avg/BAR,moldyn->gp_avg/BAR,
-              moldyn->volume,
-              (int)(t2.tv_sec-t1.tv_sec));
-       fflush(stdout);
+printf("\rsched:%d, steps:%d/%d, T:%3.1f/%3.1f P:%4.1f/%4.1f V:%6.1f (%d)",
+       sched->count,i,moldyn->total_steps,
+       moldyn->t,moldyn->t_avg,
+       moldyn->p_avg/BAR,moldyn->gp_avg/BAR,
+       moldyn->volume,
+       (int)(t2.tv_sec-t1.tv_sec));
+
+                       fflush(stdout);
 
                        /* copy over time */
                        t1=t2;
-               }
+               //}
 
                /* increase absolute time */
                moldyn->time+=moldyn->tau;
@@ -1593,8 +1709,8 @@ return 0;
 
                /* check for hooks */
                if(sched->hook) {
-                       printf("\n ## schedule hook %d/%d start ##\n",
-                              sched->count+1,sched->total_sched-1);
+                       printf("\n ## schedule hook %d start ##\n",
+                              sched->count);
                        sched->hook(moldyn,sched->hook_params);
                        printf(" ## schedule hook end ##\n");
                }
@@ -1622,6 +1738,9 @@ int velocity_verlet(t_moldyn *moldyn) {
        tau_square=moldyn->tau_square;
 
        for(i=0;i<count;i++) {
+               /* check whether fixed atom */
+               if(atom[i].attr&ATOM_ATTR_FP)
+                       continue;
                /* new positions */
                h=0.5/atom[i].mass;
                v3_scale(&delta,&(atom[i].v),tau);
@@ -1635,6 +1754,9 @@ int velocity_verlet(t_moldyn *moldyn) {
                v3_add(&(atom[i].v),&(atom[i].v),&delta);
        }
 
+       /* criticial check */
+       moldyn_bc_check(moldyn);
+
        /* neighbour list update */
        link_cell_update(moldyn);
 
@@ -1642,6 +1764,9 @@ int velocity_verlet(t_moldyn *moldyn) {
        potential_force_calc(moldyn);
 
        for(i=0;i<count;i++) {
+               /* check whether fixed atom */
+               if(atom[i].attr&ATOM_ATTR_FP)
+                       continue;
                /* again velocities [actually v(t+tau)] */
                v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
                v3_add(&(atom[i].v),&(atom[i].v),&delta);
@@ -1665,15 +1790,24 @@ int potential_force_calc(t_moldyn *moldyn) {
        t_atom *itom,*jtom,*ktom;
        t_virial *virial;
        t_linkcell *lc;
+#ifdef STATIC_LISTS
+       int *neighbour_i[27];
+       int p,q;
+       t_atom *atom;
+#else
        t_list neighbour_i[27];
        t_list neighbour_i2[27];
        t_list *this,*that;
+#endif
        u8 bc_ij,bc_ik;
        int dnlc;
 
        count=moldyn->count;
        itom=moldyn->atom;
        lc=&(moldyn->lc);
+#ifdef STATIC_LISTS
+       atom=moldyn->atom;
+#endif
 
        /* reset energy */
        moldyn->energy=0.0;
@@ -1728,14 +1862,33 @@ int potential_force_calc(t_moldyn *moldyn) {
                if(moldyn->func2b) {
                        for(j=0;j<27;j++) {
 
+                               bc_ij=(j<dnlc)?0:1;
+#ifdef STATIC_LISTS
+                               p=0;
+
+                               while(neighbour_i[j][p]!=0) {
+
+                                       jtom=&(atom[neighbour_i[j][p]]);
+                                       p++;
+
+                                       if(jtom==&(itom[i]))
+                                               continue;
+
+                                       if((jtom->attr&ATOM_ATTR_2BP)&
+                                          (itom[i].attr&ATOM_ATTR_2BP)) {
+                                               moldyn->func2b(moldyn,
+                                                              &(itom[i]),
+                                                              jtom,
+                                                              bc_ij);
+                                       }
+                               }
+#else
                                this=&(neighbour_i[j]);
                                list_reset_f(this);
 
                                if(this->start==NULL)
                                        continue;
 
-                               bc_ij=(j<dnlc)?0:1;
-
                                do {
                                        jtom=this->current->data;
 
@@ -1750,6 +1903,7 @@ int potential_force_calc(t_moldyn *moldyn) {
                                                               bc_ij);
                                        }
                                } while(list_next_f(this)!=L_NO_NEXT_ELEMENT);
+#endif
 
                        }
                }
@@ -1760,21 +1914,34 @@ int potential_force_calc(t_moldyn *moldyn) {
                        continue;
 
                /* copy the neighbour lists */
+#ifdef STATIC_LISTS
+               /* no copy needed for static lists */
+#else
                memcpy(neighbour_i2,neighbour_i,27*sizeof(t_list));
+#endif
 
                /* second loop over atoms j */
                for(j=0;j<27;j++) {
 
+                       bc_ij=(j<dnlc)?0:1;
+#ifdef STATIC_LISTS
+                       p=0;
+
+                       while(neighbour_i[j][p]!=0) {
+
+                               jtom=&(atom[neighbour_i[j][p]]);
+                               p++;
+#else
                        this=&(neighbour_i[j]);
                        list_reset_f(this);
 
                        if(this->start==NULL)
                                continue;
 
-                       bc_ij=(j<dnlc)?0:1;
-
                        do {
+
                                jtom=this->current->data;
+#endif
 
                                if(jtom==&(itom[i]))
                                        continue;
@@ -1800,17 +1967,24 @@ int potential_force_calc(t_moldyn *moldyn) {
 
                                for(k=0;k<27;k++) {
 
+                                       bc_ik=(k<dnlc)?0:1;
+#ifdef STATIC_LISTS
+                                       q=0;
+
+                                       while(neighbour_i[j][q]!=0) {
+
+                                               ktom=&(atom[neighbour_i[k][q]]);
+                                               q++;
+#else
                                        that=&(neighbour_i2[k]);
                                        list_reset_f(that);
                                        
                                        if(that->start==NULL)
                                                continue;
 
-                                       bc_ik=(k<dnlc)?0:1;
-
                                        do {
-
                                                ktom=that->current->data;
+#endif
 
                                                if(!(ktom->attr&ATOM_ATTR_3BP))
                                                        continue;
@@ -1826,9 +2000,12 @@ int potential_force_calc(t_moldyn *moldyn) {
                                                                  jtom,
                                                                  ktom,
                                                                  bc_ik|bc_ij);
-
+#ifdef STATIC_LISTS
+                                       }
+#else
                                        } while(list_next_f(that)!=\
                                                L_NO_NEXT_ELEMENT);
+#endif
 
                                }
 
@@ -1845,17 +2022,24 @@ int potential_force_calc(t_moldyn *moldyn) {
 
                                for(k=0;k<27;k++) {
 
+                                       bc_ik=(k<dnlc)?0:1;
+#ifdef STATIC_LISTS
+                                       q=0;
+
+                                       while(neighbour_i[j][q]!=0) {
+
+                                               ktom=&(atom[neighbour_i[k][q]]);
+                                               q++;
+#else
                                        that=&(neighbour_i2[k]);
                                        list_reset_f(that);
                                        
                                        if(that->start==NULL)
                                                continue;
 
-                                       bc_ik=(k<dnlc)?0:1;
-
                                        do {
-
                                                ktom=that->current->data;
+#endif
 
                                                if(!(ktom->attr&ATOM_ATTR_3BP))
                                                        continue;
@@ -1872,8 +2056,12 @@ int potential_force_calc(t_moldyn *moldyn) {
                                                                  ktom,
                                                                  bc_ik|bc_ij);
 
+#ifdef STATIC_LISTS
+                                       }
+#else
                                        } while(list_next_f(that)!=\
                                                L_NO_NEXT_ELEMENT);
+#endif
 
                                }
                                
@@ -1885,8 +2073,11 @@ int potential_force_calc(t_moldyn *moldyn) {
                                                          &(itom[i]),
                                                          jtom,bc_ij);
                                }
-                                       
+#ifdef STATIC_LISTS
+                       }
+#else
                        } while(list_next_f(this)!=L_NO_NEXT_ELEMENT);
+#endif
                
                }
                
@@ -1900,17 +2091,30 @@ int potential_force_calc(t_moldyn *moldyn) {
        }
 
 #ifdef DEBUG
-       printf("\nATOM 0: %f %f %f\n\n",itom->f.x,itom->f.y,itom->f.z);
+       //printf("\nATOM 0: %f %f %f\n\n",itom->f.x,itom->f.y,itom->f.z);
+       if(moldyn->time>DSTART&&moldyn->time<DEND) {
+               printf("force:\n");
+               printf("  x: %0.40f\n",moldyn->atom[DATOM].f.x);
+               printf("  y: %0.40f\n",moldyn->atom[DATOM].f.y);
+               printf("  z: %0.40f\n",moldyn->atom[DATOM].f.z);
+       }
 #endif
 
-       /* calculate global virial */
+       /* some postprocessing */
        for(i=0;i<count;i++) {
-               moldyn->gvir.xx+=moldyn->atom[i].r.x*moldyn->atom[i].f.x;
-               moldyn->gvir.yy+=moldyn->atom[i].r.y*moldyn->atom[i].f.y;
-               moldyn->gvir.zz+=moldyn->atom[i].r.z*moldyn->atom[i].f.z;
-               moldyn->gvir.xy+=moldyn->atom[i].r.y*moldyn->atom[i].f.x;
-               moldyn->gvir.xz+=moldyn->atom[i].r.z*moldyn->atom[i].f.x;
-               moldyn->gvir.yz+=moldyn->atom[i].r.z*moldyn->atom[i].f.y;
+               /* calculate global virial */
+               moldyn->gvir.xx+=itom[i].r.x*itom[i].f.x;
+               moldyn->gvir.yy+=itom[i].r.y*itom[i].f.y;
+               moldyn->gvir.zz+=itom[i].r.z*itom[i].f.z;
+               moldyn->gvir.xy+=itom[i].r.y*itom[i].f.x;
+               moldyn->gvir.xz+=itom[i].r.z*itom[i].f.x;
+               moldyn->gvir.yz+=itom[i].r.z*itom[i].f.y;
+
+               /* check forces regarding the given timestep */
+               if(v3_norm(&(itom[i].f))>\
+                  0.1*moldyn->nnd*itom[i].mass/moldyn->tau_square)
+                       printf("[moldyn] WARNING: pfc (high force: atom %d)\n",
+                              i);
        }
 
        return 0;
@@ -2021,6 +2225,68 @@ int moldyn_bc_check(t_moldyn *moldyn) {
  * restore function
  */
 
+int moldyn_read_save_file(t_moldyn *moldyn,char *file) {
+
+       int fd;
+       int cnt,size;
+       int fsize;
+       int corr;
+
+       fd=open(file,O_RDONLY);
+       if(fd<0) {
+               perror("[moldyn] load save file open");
+               return fd;
+       }
+
+       fsize=lseek(fd,0,SEEK_END);
+       lseek(fd,0,SEEK_SET);
+
+       size=sizeof(t_moldyn);
+
+       while(size) {
+               cnt=read(fd,moldyn,size);
+               if(cnt<0) {
+                       perror("[moldyn] load save file read (moldyn)");
+                       return cnt;
+               }
+               size-=cnt;
+       }
+
+       size=moldyn->count*sizeof(t_atom);
+
+       /* correcting possible atom data offset */
+       corr=0;
+       if(fsize!=sizeof(t_moldyn)+size) {
+               corr=fsize-sizeof(t_moldyn)-size;
+               printf("[moldyn] WARNING: lsf (illegal file size)\n");
+               printf("  moifying offset:\n");
+               printf("  - current pos: %d\n",sizeof(t_moldyn));
+               printf("  - atom size: %d\n",size);
+               printf("  - file size: %d\n",fsize);
+               printf("  => correction: %d\n",corr);
+               lseek(fd,corr,SEEK_CUR);
+       }
+
+       moldyn->atom=(t_atom *)malloc(size);
+       if(moldyn->atom==NULL) {
+               perror("[moldyn] load save file malloc (atoms)");
+               return -1;
+       }
+
+       while(size) {
+               cnt=read(fd,moldyn->atom,size);
+               if(cnt<0) {
+                       perror("[moldyn] load save file read (atoms)");
+                       return cnt;
+               }
+               size-=cnt;
+       }
+
+       // hooks etc ...
+
+       return 0;
+}
+
 int moldyn_load(t_moldyn *moldyn) {
 
        // later ...
@@ -2050,6 +2316,171 @@ int get_line(int fd,char *line,int max) {
        }
 }
 
+int pair_correlation_init(t_moldyn *moldyn,double dr) {
+
+       
+       return 0;
+}
+
+int calculate_pair_correlation(t_moldyn *moldyn,double dr,void *ptr) {
+
+       int slots;
+       double *stat;
+       int i,j;
+       t_linkcell *lc;
+#ifdef STATIC_LISTS
+       int *neighbour[27];
+       int p;
+#else
+       t_list neighbour[27];
+#endif
+       t_atom *itom,*jtom;
+       t_list *this;
+       unsigned char bc;
+       t_3dvec dist;
+       double d;
+       //double norm;
+       int o,s;
+       unsigned char ibrand;
+
+       lc=&(moldyn->lc);
+
+       slots=moldyn->cutoff/dr;
+       o=2*slots;
+
+       if(slots*dr<=moldyn->cutoff)
+               printf("[moldyn] WARNING: pcc (low #slots)\n");
+
+       printf("[moldyn] pair correlation calc info:\n");
+       printf("  time: %f\n",moldyn->time);
+       printf("  count: %d\n",moldyn->count);
+       printf("  cutoff: %f\n",moldyn->cutoff);
+       printf("  temperature: cur=%f avg=%f\n",moldyn->t,moldyn->t_avg);
+
+       if(ptr!=NULL) {
+               stat=(double *)ptr;
+       }
+       else {
+               stat=(double *)malloc(3*slots*sizeof(double));
+               if(stat==NULL) {
+                       perror("[moldyn] pair correlation malloc");
+                       return -1;
+               }
+       }
+
+       memset(stat,0,3*slots*sizeof(double));
+
+       link_cell_init(moldyn,VERBOSE);
+
+       itom=moldyn->atom;
+       
+       for(i=0;i<moldyn->count;i++) {
+               /* neighbour indexing */
+               link_cell_neighbour_index(moldyn,
+                                         (itom[i].r.x+moldyn->dim.x/2)/lc->x,
+                                         (itom[i].r.y+moldyn->dim.y/2)/lc->x,
+                                         (itom[i].r.z+moldyn->dim.z/2)/lc->x,
+                                         neighbour);
+
+               /* brand of atom i */
+               ibrand=itom[i].brand;
+       
+               for(j=0;j<27;j++) {
+
+                       bc=(j<lc->dnlc)?0:1;
+
+#ifdef STATIC_LISTS
+                       p=0;
+
+                       while(neighbour[j][p]!=0) {
+
+                               jtom=&(moldyn->atom[neighbour[j][p]]);
+                               p++;
+#else
+                       this=&(neighbour[j]);
+                       list_reset_f(this);
+
+                       if(this->start==NULL)
+                               continue;
+
+                       do {
+
+                               jtom=this->current->data;
+#endif
+                               /* only count pairs once,
+                                * skip same atoms */
+                               if(itom[i].tag>=jtom->tag)
+                                       continue;
+
+                               /*
+                                * pair correlation calc
+                                */
+
+                               /* distance */
+                               v3_sub(&dist,&(jtom->r),&(itom[i].r));
+                               if(bc) check_per_bound(moldyn,&dist);
+                               d=v3_absolute_square(&dist);
+
+                               /* ignore if greater or equal cutoff */
+                               if(d>=moldyn->cutoff_square)
+                                       continue;
+
+                               /* fill the slots */
+                               d=sqrt(d);
+                               s=(int)(d/dr);
+
+                               /* should never happen but it does 8) -
+                                * related to -ffloat-store problem! */
+                               if(s>=slots) {
+                                       printf("[moldyn] WARNING: pcc (%d/%d)",
+                                              s,slots);
+                                       printf("\n");
+                                       s=slots-1;
+                               }
+
+                               if(ibrand!=jtom->brand) {
+                                       /* mixed */
+                                       stat[s]+=1;
+                               }
+                               else {
+                                       /* type a - type a bonds */
+                                       if(ibrand==0)
+                                               stat[s+slots]+=1;
+                                       else
+                                       /* type b - type b bonds */
+                                               stat[s+o]+=1;
+                               }
+#ifdef STATIC_LISTS
+                       }
+#else
+                       } while(list_next_f(this)!=L_NO_NEXT_ELEMENT);
+#endif
+               }
+       }
+
+       /* normalization 
+       for(i=1;i<slots;i++) {
+                // normalization: 4 pi r r dr
+                // here: not double counting pairs -> 2 pi r r dr
+               norm=2*M_PI*moldyn->count*(i*dr*i*dr)*dr;
+               stat[i]/=norm;
+               stat[slots+i]/=norm;
+               stat[o+i]/=norm;
+       }
+       */
+
+       if(ptr==NULL) {
+               /* todo: store/print pair correlation function */
+               free(stat);
+       }
+
+       free(moldyn->atom);
+
+       link_cell_shutdown(moldyn);
+
+       return 0;
+}
+
 int analyze_bonds(t_moldyn *moldyn) {
 
        
@@ -2062,30 +2493,44 @@ int analyze_bonds(t_moldyn *moldyn) {
  * visualization code
  */
 
-int visual_init(t_visual *v,char *filebase) {
-
-       char file[128+8];
+int visual_init(t_moldyn *moldyn,char *filebase) {
 
-       strncpy(v->fb,filebase,128);
-       memset(file,0,128+8);
+       strncpy(moldyn->vis.fb,filebase,128);
 
        return 0;
 }
 
-int visual_atoms(t_visual *v,double time,t_atom *atom,int n) {
+int visual_atoms(t_moldyn *moldyn) {
 
-       int i,fd;
+       int i,j,fd;
        char file[128+64];
        t_3dvec dim;
        double help;
+       t_visual *v;
+       t_atom *atom;
+       t_atom *btom;
+       t_linkcell *lc;
+#ifdef STATIC_LISTS
+       int *neighbour[27];
+       int p;
+#else
+       t_list neighbour[27];
+#endif
+       u8 bc;
+       t_3dvec dist;
+       double d2;
+       u8 brand;
 
+       v=&(moldyn->vis);
        dim.x=v->dim.x;
        dim.y=v->dim.y;
        dim.z=v->dim.z;
+       atom=moldyn->atom;
+       lc=&(moldyn->lc);
 
        help=(dim.x+dim.y);
 
-       sprintf(file,"%s/atomic_conf_%07.f.xyz",v->fb,time);
+       sprintf(file,"%s/atomic_conf_%07.f.xyz",v->fb,moldyn->time);
        fd=open(file,O_WRONLY|O_CREAT|O_TRUNC,S_IRUSR|S_IWUSR);
        if(fd<0) {
                perror("open visual save file fd");
@@ -2093,15 +2538,78 @@ int visual_atoms(t_visual *v,double time,t_atom *atom,int n) {
        }
 
        /* write the actual data file */
+
+       // povray header
        dprintf(fd,"# [P] %d %07.f <%f,%f,%f>\n",
-               n,time,help/40.0,help/40.0,-0.8*help);
-       for(i=0;i<n;i++)
+               moldyn->count,moldyn->time,help/40.0,help/40.0,-0.8*help);
+
+       // atomic configuration
+       for(i=0;i<moldyn->count;i++) {
+               // atom type, positions, color and kinetic energy
                dprintf(fd,"%s %f %f %f %s %f\n",pse_name[atom[i].element],
                                                 atom[i].r.x,
                                                 atom[i].r.y,
                                                 atom[i].r.z,
                                                 pse_col[atom[i].element],
                                                 atom[i].ekin);
+
+               /*
+                * bond detection should usually be done by potential
+                * functions. brrrrr! EVIL!
+                * 
+                * todo: potentials need to export a 'find_bonds' function!
+                */
+
+               // bonds between atoms
+               if(!(atom[i].attr&ATOM_ATTR_VB))
+                       continue;
+               link_cell_neighbour_index(moldyn,
+                                         (atom[i].r.x+moldyn->dim.x/2)/lc->x,
+                                         (atom[i].r.y+moldyn->dim.y/2)/lc->y,
+                                         (atom[i].r.z+moldyn->dim.z/2)/lc->z,
+                                         neighbour);
+               for(j=0;j<27;j++) {
+                       bc=j<lc->dnlc?0:1;
+#ifdef STATIC_LISTS
+                       p=0;
+                       while(neighbour[j][p]!=0) {
+                               btom=&(atom[neighbour[j][p]]);
+                               p++;
+#else
+                       list_reset_f(&neighbour[j]);
+                       if(neighbour[j].start==NULL)
+                               continue;
+                       do {
+                               btom=neighbour[j].current->data;
+#endif
+                               if(btom==&atom[i])      // skip identical atoms
+                                       continue;
+                               //if(btom<&atom[i])     // skip half of them
+                               //      continue;
+                               v3_sub(&dist,&(atom[i].r),&(btom->r));
+                               if(bc) check_per_bound(moldyn,&dist);
+                               d2=v3_absolute_square(&dist);
+                               brand=atom[i].brand;
+                               if(brand==btom->brand) {
+                                       if(d2>moldyn->bondlen[brand])
+                                               continue;
+                               }
+                               else {
+                                       if(d2>moldyn->bondlen[2])
+                                               continue;
+                               }
+                               dprintf(fd,"# [B] %f %f %f %f %f %f\n",
+                                       atom[i].r.x,atom[i].r.y,atom[i].r.z,
+                                       btom->r.x,btom->r.y,btom->r.z);
+#ifdef STATIC_LISTS
+                       }
+#else
+                       } while(list_next_f(&neighbour[j])!=L_NO_NEXT_ELEMENT);
+#endif
+               }
+       }
+
+       // boundaries
        if(dim.x) {
                dprintf(fd,"# [D] %f %f %f %f %f %f\n",
                        -dim.x/2,-dim.y/2,-dim.z/2,