+int scale_dim(t_moldyn *moldyn,double scale,u8 x,u8 y,u8 z) {
+
+ t_3dvec *dim;
+
+ dim=&(moldyn->dim);
+
+ if(x) dim->x*=scale;
+ if(y) dim->y*=scale;
+ if(z) dim->z*=scale;
+
+ return 0;
+}
+
+int scale_atoms(t_moldyn *moldyn,double scale,u8 x,u8 y,u8 z) {
+
+ int i;
+ t_3dvec *r;
+
+ for(i=0;i<moldyn->count;i++) {
+ r=&(moldyn->atom[i].r);
+ if(x) r->x*=scale;
+ if(y) r->y*=scale;
+ if(z) r->z*=scale;
+ }
+
+ return 0;
+}
+
+int scale_volume(t_moldyn *moldyn) {
+
+ t_atom *atom;
+ t_3dvec *dim,*vdim;
+ double scale,v;
+ t_virial virial;
+ t_linkcell *lc;
+ int i;
+
+ atom=moldyn->atom;
+ dim=&(moldyn->dim);
+ vdim=&(moldyn->vis.dim);
+ lc=&(moldyn->lc);
+
+ memset(&virial,0,sizeof(t_virial));
+
+ for(i=0;i<moldyn->count;i++) {
+ virial.xx+=atom[i].virial.xx;
+ virial.yy+=atom[i].virial.yy;
+ virial.zz+=atom[i].virial.zz;
+ virial.xy+=atom[i].virial.xy;
+ virial.xz+=atom[i].virial.xz;
+ virial.yz+=atom[i].virial.yz;
+ }
+
+ /* just a guess so far ... */
+ v=virial.xx+virial.yy+virial.zz;
+
+printf("%f\n",v);
+ /* get pressure from virial */
+ moldyn->p=moldyn->count*K_BOLTZMANN*moldyn->t+ONE_THIRD*v;
+ moldyn->p/=moldyn->volume;
+printf("%f | %f\n",moldyn->p/(ATM),moldyn->p_ref/ATM);
+
+ /* scale factor */
+ if(moldyn->pt_scale&P_SCALE_BERENDSEN)
+ scale=3*sqrt(1-(moldyn->p_ref-moldyn->p)/moldyn->p_tc);
+ else
+ /* should actually never be used */
+ scale=pow(moldyn->p/moldyn->p_ref,1.0/3.0);
+
+printf("scale = %f\n",scale);
+ /* actual scaling */
+ dim->x*=scale;
+ dim->y*=scale;
+ dim->z*=scale;
+ if(vdim->x) vdim->x=dim->x;
+ if(vdim->y) vdim->y=dim->y;
+ if(vdim->z) vdim->z=dim->z;
+ moldyn->volume*=(scale*scale*scale);
+
+ /* check whether we need a new linkcell init */
+ if((dim->x/moldyn->cutoff!=lc->nx)||
+ (dim->y/moldyn->cutoff!=lc->ny)||
+ (dim->z/moldyn->cutoff!=lc->nx)) {
+ link_cell_shutdown(moldyn);
+ link_cell_init(moldyn);
+ }
+
+ return 0;
+
+}
+
+double get_e_kin(t_moldyn *moldyn) {
+
+ int i;
+ t_atom *atom;
+
+ atom=moldyn->atom;
+ moldyn->ekin=0.0;
+
+ for(i=0;i<moldyn->count;i++)
+ moldyn->ekin+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
+
+ return moldyn->ekin;
+}
+
+double update_e_kin(t_moldyn *moldyn) {
+
+ return(get_e_kin(moldyn));
+}
+
+double get_total_energy(t_moldyn *moldyn) {
+
+ return(moldyn->ekin+moldyn->energy);
+}
+
+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<moldyn->count;i++) {
+ v3_scale(&p,&(atom[i].v),atom[i].mass);
+ v3_add(&p_total,&p_total,&p);
+ }
+
+ return p_total;
+}
+
+double estimate_time_step(t_moldyn *moldyn,double nn_dist) {
+
+ double tau;
+
+ /* nn_dist is the nearest neighbour distance */
+
+ tau=(0.05*nn_dist*moldyn->atom[0].mass)/sqrt(3.0*K_BOLTZMANN*moldyn->t);
+
+ return tau;
+}
+
+/*
+ * numerical tricks
+ */
+
+/* linked list / cell method */
+
+int link_cell_init(t_moldyn *moldyn) {
+
+ t_linkcell *lc;
+ int i;
+
+ lc=&(moldyn->lc);
+
+ /* partitioning the md cell */
+ lc->nx=moldyn->dim.x/moldyn->cutoff;
+ lc->x=moldyn->dim.x/lc->nx;
+ lc->ny=moldyn->dim.y/moldyn->cutoff;
+ 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;
+ lc->subcell=malloc(lc->cells*sizeof(t_list));
+
+ if(lc->cells<27)
+ printf("[moldyn] FATAL: less then 27 subcells!\n");
+
+ printf("[moldyn] initializing linked cells (%d)\n",lc->cells);
+
+ for(i=0;i<lc->cells;i++)
+ list_init_f(&(lc->subcell[i]));
+
+ link_cell_update(moldyn);
+
+ return 0;
+}
+
+int link_cell_update(t_moldyn *moldyn) {
+
+ int count,i,j,k;
+ int nx,ny;
+ t_atom *atom;
+ t_linkcell *lc;
+ double x,y,z;
+
+ atom=moldyn->atom;
+ lc=&(moldyn->lc);
+
+ 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++)
+ list_destroy_f(&(lc->subcell[i]));
+
+ 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);
+ list_add_immediate_f(&(moldyn->lc.subcell[i+j*nx+k*nx*ny]),
+ &(atom[count]));
+ }
+
+ return 0;
+}
+
+int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
+
+ t_linkcell *lc;
+ int a;
+ int count1,count2;
+ int ci,cj,ck;
+ int nx,ny,nz;
+ int x,y,z;
+ u8 bx,by,bz;
+
+ lc=&(moldyn->lc);
+ nx=lc->nx;
+ ny=lc->ny;
+ nz=lc->nz;
+ count1=1;
+ count2=27;
+ a=nx*ny;
+
+ cell[0]=lc->subcell[i+j*nx+k*a];
+ for(ci=-1;ci<=1;ci++) {
+ bx=0;
+ x=i+ci;
+ if((x<0)||(x>=nx)) {
+ x=(x+nx)%nx;
+ bx=1;
+ }
+ for(cj=-1;cj<=1;cj++) {
+ by=0;
+ y=j+cj;
+ if((y<0)||(y>=ny)) {
+ y=(y+ny)%ny;
+ by=1;
+ }
+ for(ck=-1;ck<=1;ck++) {
+ bz=0;
+ z=k+ck;
+ if((z<0)||(z>=nz)) {
+ z=(z+nz)%nz;
+ bz=1;
+ }
+ if(!(ci|cj|ck)) continue;
+ if(bx|by|bz) {
+ cell[--count2]=lc->subcell[x+y*nx+z*a];
+ }
+ else {
+ cell[count1++]=lc->subcell[x+y*nx+z*a];
+ }
+ }
+ }
+ }
+
+ lc->dnlc=count1;
+
+ return count1;
+}
+
+int link_cell_shutdown(t_moldyn *moldyn) {
+
+ int i;
+ t_linkcell *lc;
+
+ lc=&(moldyn->lc);
+
+ for(i=0;i<lc->nx*lc->ny*lc->nz;i++)
+ list_destroy_f(&(moldyn->lc.subcell[i]));
+
+ free(lc->subcell);
+
+ 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->total_sched);
+
+ ptr=realloc(schedule->runs,count*sizeof(int));
+ if(!ptr) {
+ perror("[moldyn] realloc (runs)");
+ return -1;
+ }
+ schedule->runs=ptr;
+ schedule->runs[count-1]=runs;
+
+ ptr=realloc(schedule->tau,count*sizeof(double));
+ if(!ptr) {
+ perror("[moldyn] realloc (tau)");
+ return -1;
+ }
+ schedule->tau=ptr;
+ schedule->tau[count-1]=tau;
+
+ printf("[moldyn] schedule added:\n");
+ printf(" number: %d | runs: %d | tau: %f\n",count-1,runs,tau);
+
+
+ return 0;
+}
+
+int moldyn_set_schedule_hook(t_moldyn *moldyn,set_hook hook,void *hook_params) {
+
+ moldyn->schedule.hook=hook;
+ moldyn->schedule.hook_params=hook_params;
+
+ return 0;
+}
+
+/*
+ *
+ * 'integration of newtons equation' - algorithms
+ *
+ */
+
+/* start the integration */
+
+int moldyn_integrate(t_moldyn *moldyn) {
+
+ int i;
+ unsigned int e,m,s,v;
+ t_3dvec p;
+ t_moldyn_schedule *sched;
+ t_atom *atom;
+ int fd;
+ char dir[128];
+ double ds;
+
+ sched=&(moldyn->schedule);
+ atom=moldyn->atom;
+
+ /* initialize linked cell method */
+ link_cell_init(moldyn);
+
+ /* logging & visualization */
+ e=moldyn->ewrite;
+ m=moldyn->mwrite;
+ s=moldyn->swrite;
+ v=moldyn->vwrite;
+
+ /* sqaure of some variables */
+ moldyn->tau_square=moldyn->tau*moldyn->tau;
+ moldyn->cutoff_square=moldyn->cutoff*moldyn->cutoff;
+
+ /* calculate initial forces */
+ 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, ignore */
+ moldyn->debug=0;
+
+ /* tell the world */
+ printf("[moldyn] integration start, go get a coffee ...\n");
+
+ /* executing the schedule */
+ for(sched->count=0;sched->count<sched->total_sched;sched->count++) {
+
+ /* setting amount of runs and finite time step size */
+ moldyn->tau=sched->tau[sched->count];
+ moldyn->tau_square=moldyn->tau*moldyn->tau;
+ moldyn->time_steps=sched->runs[sched->count];
+
+ /* 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);
+ if(moldyn->pt_scale&(P_SCALE_BERENDSEN|P_SCALE_DIRECT))
+ scale_volume(moldyn);
+
+printf("-> %f\n",thermodynamic_pressure_calc(moldyn)/ATM);
+
+ /* check for log & visualization */
+ if(e) {
+ if(!(i%e))
+ update_e_kin(moldyn);
+ dprintf(moldyn->efd,
+ "%f %f %f %f\n",
+ moldyn->time,moldyn->ekin,
+ moldyn->energy,
+ get_total_energy(moldyn));
+ }
+ if(m) {
+ if(!(i%m)) {
+ p=get_total_p(moldyn);
+ dprintf(moldyn->mfd,
+ "%f %f\n",moldyn->time,v3_norm(&p));
+ }
+ }
+ if(s) {
+ if(!(i%s)) {
+ snprintf(dir,128,"%s/s-%07.f.save",
+ moldyn->vlsdir,moldyn->time);
+ fd=open(dir,O_WRONLY|O_TRUNC|O_CREAT);
+ if(fd<0) perror("[moldyn] save fd open");
+ else {
+ write(fd,moldyn,sizeof(t_moldyn));
+ write(fd,moldyn->atom,
+ moldyn->count*sizeof(t_atom));
+ }
+ close(fd);
+ }
+ }
+ if(v) {
+ if(!(i%v)) {
+ visual_atoms(&(moldyn->vis),moldyn->time,
+ moldyn->atom,moldyn->count);
+ printf("\rsched: %d, steps: %d, debug: %d",
+ sched->count,i,moldyn->debug);
+ fflush(stdout);
+ }
+ }
+
+ /* increase absolute time */
+ moldyn->time+=moldyn->tau;
+
+ }
+
+ /* check for hooks */
+ if(sched->hook)
+ sched->hook(moldyn,sched->hook_params);
+
+ /* get a new info line */
+ printf("\n");
+
+ }
+
+ return 0;
+}
+
+/* velocity verlet */
+
+int velocity_verlet(t_moldyn *moldyn) {
+
+ int i,count;
+ double tau,tau_square,h;
+ t_3dvec delta;
+ t_atom *atom;
+
+ atom=moldyn->atom;
+ count=moldyn->count;
+ tau=moldyn->tau;
+ tau_square=moldyn->tau_square;
+
+ for(i=0;i<count;i++) {
+ /* new positions */
+ h=0.5/atom[i].mass;
+ v3_scale(&delta,&(atom[i].v),tau);
+ v3_add(&(atom[i].r),&(atom[i].r),&delta);
+ v3_scale(&delta,&(atom[i].f),h*tau_square);
+ v3_add(&(atom[i].r),&(atom[i].r),&delta);
+ check_per_bound(moldyn,&(atom[i].r));
+
+ /* velocities [actually v(t+tau/2)] */
+ v3_scale(&delta,&(atom[i].f),h*tau);
+ v3_add(&(atom[i].v),&(atom[i].v),&delta);
+ }
+
+ /* neighbour list update */
+ link_cell_update(moldyn);
+
+ /* forces depending on chosen potential */
+ potential_force_calc(moldyn);
+
+ for(i=0;i<count;i++) {
+ /* 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);
+ }
+
+ return 0;
+}
+
+
+/*
+ *
+ * potentials & corresponding forces & virial routine
+ *
+ */
+
+/* generic potential and force calculation */
+
+int potential_force_calc(t_moldyn *moldyn) {
+
+ int i,j,k,count;
+ t_atom *itom,*jtom,*ktom;
+ t_virial *virial;
+ t_linkcell *lc;
+ t_list neighbour_i[27];
+ t_list neighbour_i2[27];
+ t_list *this,*that;
+ u8 bc_ij,bc_ik;
+ int dnlc;
+
+ count=moldyn->count;
+ itom=moldyn->atom;
+ lc=&(moldyn->lc);
+
+ /* reset energy */
+ moldyn->energy=0.0;
+
+ /* reset virial */
+ moldyn->vt1=0.0;
+
+ /* reset force, site energy and virial of every atom */
+ for(i=0;i<count;i++) {
+
+ /* reset force */
+ v3_zero(&(itom[i].f));
+
+ /* reset virial */
+ virial=(&(itom[i].virial));
+ virial->xx=0.0;
+ virial->yy=0.0;
+ virial->zz=0.0;
+ virial->xy=0.0;
+ virial->xz=0.0;
+ virial->yz=0.0;
+
+ /* reset site energy */
+ itom[i].e=0.0;
+
+ }
+
+ /* get energy,force and virial of every atom */
+ for(i=0;i<count;i++) {
+
+ /* single particle potential/force */
+ if(itom[i].attr&ATOM_ATTR_1BP)
+ moldyn->func1b(moldyn,&(itom[i]));
+
+ if(!(itom[i].attr&(ATOM_ATTR_2BP|ATOM_ATTR_3BP)))
+ continue;
+
+ /* 2 body pair potential/force */
+
+ 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;
+
+ for(j=0;j<27;j++) {
+
+ this=&(neighbour_i[j]);
+ list_reset_f(this);
+
+ if(this->start==NULL)
+ continue;
+
+ bc_ij=(j<dnlc)?0:1;
+
+ do {
+ jtom=this->current->data;
+
+ 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);
+ }
+
+ /* 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_f(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;
+
+ if(ktom==&(itom[i]))
+ continue;
+
+ moldyn->func3b(moldyn,
+ &(itom[i]),
+ jtom,
+ ktom,
+ bc_ik|bc_ij);
+
+ } while(list_next_f(that)!=\
+ L_NO_NEXT_ELEMENT);
+
+ }
+
+ /* 2bp post function */
+ if(moldyn->func2b_post) {
+ moldyn->func2b_post(moldyn,
+ &(itom[i]),
+ jtom,bc_ij);
+ }
+
+ } while(list_next_f(this)!=L_NO_NEXT_ELEMENT);
+
+ }
+
+ }
+#ifdef DEBUG
+printf("\n\n");
+#endif
+#ifdef VDEBUG
+printf("\n\n");
+#endif
+
+temperature_calc(moldyn);
+pressure_calc(moldyn);
+ideal_gas_law_pressure(moldyn);
+
+ return 0;
+}
+
+/*
+ * virial calculation
+ */
+
+inline int virial_calc(t_atom *a,t_3dvec *f,t_3dvec *d) {
+
+ a->virial.xx-=f->x*d->x;
+ a->virial.yy-=f->y*d->y;
+ a->virial.zz-=f->z*d->z;
+ a->virial.xy-=f->x*d->y;
+ a->virial.xz-=f->x*d->z;
+ a->virial.yz-=f->y*d->z;
+
+ return 0;
+}
+
+/*
+ * periodic boundayr checking
+ */
+
+inline int check_per_bound(t_moldyn *moldyn,t_3dvec *a) {
+
+ double x,y,z;
+ t_3dvec *dim;
+
+ dim=&(moldyn->dim);
+
+ x=dim->x/2;
+ y=dim->y/2;
+ z=dim->z/2;
+
+ 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;
+}
+
+
+/*
+ * example potentials
+ */
+
+/* harmonic oscillator potential and force */
+
+int harmonic_oscillator(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
+
+ t_ho_params *params;
+ t_3dvec force,distance;
+ double d,f;
+ double sc,equi_dist;
+
+ params=moldyn->pot2b_params;
+ sc=params->spring_constant;
+ equi_dist=params->equilibrium_distance;
+
+ if(ai<aj) return 0;
+
+ v3_sub(&distance,&(aj->r),&(ai->r));
+
+ if(bc) check_per_bound(moldyn,&distance);
+ d=v3_norm(&distance);
+ if(d<=moldyn->cutoff) {
+ moldyn->energy+=(0.5*sc*(d-equi_dist)*(d-equi_dist));
+ /* f = -grad E; grad r_ij = -1 1/r_ij distance */
+ f=sc*(1.0-equi_dist/d);
+ v3_scale(&force,&distance,f);
+ v3_add(&(ai->f),&(ai->f),&force);
+ virial_calc(ai,&force,&distance);
+ virial_calc(aj,&force,&distance); /* f and d signe switched */
+ v3_scale(&force,&distance,-f);
+ v3_add(&(aj->f),&(aj->f),&force);
+ }
+
+ return 0;
+}
+
+/* lennard jones potential & force for one sort of atoms */
+
+int lennard_jones(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
+
+ t_lj_params *params;
+ t_3dvec force,distance;
+ double d,h1,h2;
+ double eps,sig6,sig12;
+
+ params=moldyn->pot2b_params;
+ eps=params->epsilon4;
+ sig6=params->sigma6;
+ sig12=params->sigma12;
+
+ if(ai<aj) return 0;
+
+ v3_sub(&distance,&(aj->r),&(ai->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 */
+ moldyn->energy+=(eps*(sig12*h1-sig6*h2)-params->uc);
+ 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(&(aj->f),&(aj->f),&force);
+ v3_scale(&force,&distance,-1.0*d); /* f = - grad E */
+ v3_add(&(ai->f),&(ai->f),&force);
+ virial_calc(ai,&force,&distance);
+ virial_calc(aj,&force,&distance); /* f and d signe switched */
+ moldyn->vt1-=v3_scalar_product(&force,&distance);
+ }
+
+ return 0;
+}
+
+/*
+ * tersoff potential & force for 2 sorts of atoms
+ */
+
+/* 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->S2[0]=p->S[0]*p->S[0];
+ p->S2[1]=p->S[1]*p->S[1];
+ p->Smixed=sqrt(p->S[0]*p->S[1]);
+ p->S2mixed=p->Smixed*p->Smixed;
+ 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 (A) | %f | %f | %f\n",p->S[0],p->S[1],p->Smixed);
+ printf(" R (A) | %f | %f | %f\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);
+
+ return 0;
+}
+
+/* tersoff 1 body part */
+int tersoff_mult_1bp(t_moldyn *moldyn,t_atom *ai) {
+
+ int brand;
+ t_tersoff_mult_params *params;
+ t_tersoff_exchange *exchange;
+
+ brand=ai->brand;
+ params=moldyn->pot1b_params;
+ exchange=&(params->exchange);
+
+ /*
+ * simple: point constant parameters only depending on atom i to
+ * their right values
+ */
+
+ exchange->beta_i=&(params->beta[brand]);
+ exchange->n_i=&(params->n[brand]);
+ exchange->c_i=&(params->c[brand]);
+ exchange->d_i=&(params->d[brand]);
+ exchange->h_i=&(params->h[brand]);
+
+ exchange->betaini=pow(*(exchange->beta_i),*(exchange->n_i));
+ exchange->ci2=params->c[brand]*params->c[brand];
+ exchange->di2=params->d[brand]*params->d[brand];
+ exchange->ci2di2=exchange->ci2/exchange->di2;
+
+ 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,d_ij2;
+ double A,B,R,S,S2,lambda,mu;
+ double f_r,df_r;
+ double f_c,df_c;
+ int brand;
+ double s_r;
+ double arg;
+
+ params=moldyn->pot2b_params;
+ brand=aj->brand;
+ exchange=&(params->exchange);
+
+ /* clear 3bp and 2bp post run */
+ exchange->run3bp=0;
+ exchange->run2bp_post=0;
+
+ /* reset S > r > R mark */
+ exchange->d_ij_between_rs=0;
+
+ /*
+ * calc of 2bp contribution of V_ij and dV_ij/ji
+ *
+ * for Vij and dV_ij we need:
+ * - f_c_ij, df_c_ij
+ * - f_r_ij, df_r_ij
+ *
+ * for dV_ji we need:
+ * - f_c_ji = f_c_ij, df_c_ji = df_c_ij
+ * - f_r_ji = f_r_ij; df_r_ji = df_r_ij
+ *
+ */
+
+ /* constants */
+ if(brand==ai->brand) {
+ S=params->S[brand];
+ S2=params->S2[brand];
+ R=params->R[brand];
+ A=params->A[brand];
+ B=params->B[brand];
+ lambda=params->lambda[brand];
+ mu=params->mu[brand];
+ exchange->chi=1.0;
+ }
+ else {
+ S=params->Smixed;
+ S2=params->S2mixed;
+ R=params->Rmixed;
+ A=params->Amixed;
+ B=params->Bmixed;
+ lambda=params->lambda_m;
+ mu=params->mu_m;
+ params->exchange.chi=params->chi;
+ }
+
+ /* dist_ij, d_ij */
+ v3_sub(&dist_ij,&(aj->r),&(ai->r));
+ if(bc) check_per_bound(moldyn,&dist_ij);
+ d_ij2=v3_absolute_square(&dist_ij);
+
+ /* if d_ij2 > S2 => no force & potential energy contribution */
+ if(d_ij2>S2)
+ return 0;
+
+ /* now we will need the distance */
+ //d_ij=v3_norm(&dist_ij);
+ d_ij=sqrt(d_ij2);
+
+ /* save for use in 3bp */
+ exchange->d_ij=d_ij;
+ exchange->d_ij2=d_ij2;
+ exchange->dist_ij=dist_ij;
+
+ /* more constants */
+ exchange->beta_j=&(params->beta[brand]);
+ exchange->n_j=&(params->n[brand]);
+ exchange->c_j=&(params->c[brand]);
+ exchange->d_j=&(params->d[brand]);
+ exchange->h_j=&(params->h[brand]);
+ if(brand==ai->brand) {
+ exchange->betajnj=exchange->betaini;
+ exchange->cj2=exchange->ci2;
+ exchange->dj2=exchange->di2;
+ exchange->cj2dj2=exchange->ci2di2;
+ }
+ else {
+ exchange->betajnj=pow(*(exchange->beta_j),*(exchange->n_j));
+ exchange->cj2=params->c[brand]*params->c[brand];
+ exchange->dj2=params->d[brand]*params->d[brand];
+ exchange->cj2dj2=exchange->cj2/exchange->dj2;
+ }
+
+ /* f_r_ij = f_r_ji, df_r_ij = df_r_ji */
+ f_r=A*exp(-lambda*d_ij);
+ df_r=lambda*f_r/d_ij;
+
+ /* f_a, df_a calc (again, same for ij and ji) | save for later use! */
+ exchange->f_a=-B*exp(-mu*d_ij);
+ exchange->df_a=mu*exchange->f_a/d_ij;
+
+ /* f_c, df_c calc (again, same for ij and ji) */
+ if(d_ij<R) {
+ /* f_c = 1, df_c = 0 */
+ f_c=1.0;
+ df_c=0.0;
+ /* two body contribution (ij, ji) */
+ 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));
+ /* two body contribution (ij, ji) */
+ v3_scale(&force,&dist_ij,-df_c*f_r-df_r*f_c);
+ /* tell 3bp that S > r > R */
+ exchange->d_ij_between_rs=1;
+ }
+
+ /* add forces of 2bp (ij, ji) contribution
+ * dVij = dVji and we sum up both: no 1/2) */
+ v3_add(&(ai->f),&(ai->f),&force);
+
+ /* virial */
+ ai->virial.xx-=force.x*dist_ij.x;
+ ai->virial.yy-=force.y*dist_ij.y;
+ ai->virial.zz-=force.z*dist_ij.z;
+ ai->virial.xy-=force.x*dist_ij.y;
+ ai->virial.xz-=force.x*dist_ij.z;
+ ai->virial.yz-=force.y*dist_ij.z;
+
+#ifdef DEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVij, dVji (2bp) contrib:\n");
+ printf("%f | %f\n",force.x,ai->f.x);
+ printf("%f | %f\n",force.y,ai->f.y);
+ printf("%f | %f\n",force.z,ai->f.z);
+}
+#endif
+#ifdef VDEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVij, dVji (2bp) contrib:\n");
+ printf("%f | %f\n",force.x*dist_ij.x,ai->virial.xx);
+ printf("%f | %f\n",force.y*dist_ij.y,ai->virial.yy);
+ printf("%f | %f\n",force.z*dist_ij.z,ai->virial.zz);
+}
+#endif
+
+ /* energy 2bp contribution (ij, ji) is 0.5 f_r f_c ... */
+ moldyn->energy+=(0.5*f_r*f_c);
+
+ /* save for use in 3bp */
+ exchange->f_c=f_c;
+ exchange->df_c=df_c;
+
+ /* enable the run of 3bp function and 2bp post processing */
+ exchange->run3bp=1;
+ exchange->run2bp_post=1;
+
+ /* reset 3bp sums */
+ exchange->zeta_ij=0.0;
+ exchange->zeta_ji=0.0;
+ v3_zero(&(exchange->dzeta_ij));
+ v3_zero(&(exchange->dzeta_ji));
+
+ return 0;
+}
+
+/* tersoff 2 body post part */
+
+int tersoff_mult_post_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
+
+ /*
+ * here we have to allow for the 3bp sums
+ *
+ * that is:
+ * - zeta_ij, dzeta_ij
+ * - zeta_ji, dzeta_ji
+ *
+ * to compute the 3bp contribution to:
+ * - Vij, dVij
+ * - dVji
+ *
+ */
+
+ t_tersoff_mult_params *params;
+ t_tersoff_exchange *exchange;
+
+ t_3dvec force,temp;
+ t_3dvec *dist_ij;
+ double b,db,tmp;
+ double f_c,df_c,f_a,df_a;
+ double chi,ni,betaini,nj,betajnj;
+ double zeta;
+
+ 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;
+
+ f_c=exchange->f_c;
+ df_c=exchange->df_c;
+ f_a=exchange->f_a;
+ df_a=exchange->df_a;
+ betaini=exchange->betaini;
+ betajnj=exchange->betajnj;
+ ni=*(exchange->n_i);
+ nj=*(exchange->n_j);
+ chi=exchange->chi;
+ dist_ij=&(exchange->dist_ij);
+
+ /* Vij and dVij */
+ zeta=exchange->zeta_ij;
+ if(zeta==0.0) {
+ moldyn->debug++; /* just for debugging ... */
+ b=chi;
+ v3_scale(&force,dist_ij,df_a*b*f_c);
+ }
+ else {
+ tmp=betaini*pow(zeta,ni-1.0); /* beta^n * zeta^n-1 */
+ b=(1+zeta*tmp); /* 1 + beta^n zeta^n */
+ db=chi*pow(b,-1.0/(2*ni)-1); /* x(...)^(-1/2n - 1) */
+ b=db*b; /* b_ij */
+ db*=-0.5*tmp; /* db_ij */
+ v3_scale(&force,&(exchange->dzeta_ij),f_a*db);
+ v3_scale(&temp,dist_ij,df_a*b);
+ v3_add(&force,&force,&temp);
+ v3_scale(&force,&force,f_c);
+ }
+ v3_scale(&temp,dist_ij,df_c*b*f_a);
+ v3_add(&force,&force,&temp);
+ v3_scale(&force,&force,-0.5);
+
+ /* add force */
+ v3_add(&(ai->f),&(ai->f),&force);
+
+ /* virial */
+ ai->virial.xx-=force.x*dist_ij->x;
+ ai->virial.yy-=force.y*dist_ij->y;
+ ai->virial.zz-=force.z*dist_ij->z;
+ ai->virial.xy-=force.x*dist_ij->y;
+ ai->virial.xz-=force.x*dist_ij->z;
+ ai->virial.yz-=force.y*dist_ij->z;
+
+#ifdef DEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVij (3bp) contrib:\n");
+ printf("%f | %f\n",force.x,ai->f.x);
+ printf("%f | %f\n",force.y,ai->f.y);
+ printf("%f | %f\n",force.z,ai->f.z);
+}
+#endif
+#ifdef VDEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVij (3bp) contrib:\n");
+ printf("%f | %f\n",force.x*dist_ij->x,ai->virial.xx);
+ printf("%f | %f\n",force.y*dist_ij->y,ai->virial.yy);
+ printf("%f | %f\n",force.z*dist_ij->z,ai->virial.zz);
+}
+#endif
+
+ /* add energy of 3bp sum */
+ moldyn->energy+=(0.5*f_c*b*f_a);
+
+ /* dVji */
+ zeta=exchange->zeta_ji;
+ if(zeta==0.0) {
+ moldyn->debug++;
+ b=chi;
+ v3_scale(&force,dist_ij,df_a*b*f_c);
+ }
+ else {
+ tmp=betajnj*pow(zeta,nj-1.0); /* beta^n * zeta^n-1 */
+ b=(1+zeta*tmp); /* 1 + beta^n zeta^n */
+ db=chi*pow(b,-1.0/(2*nj)-1); /* x(...)^(-1/2n - 1) */
+ b=db*b; /* b_ij */
+ db*=-0.5*tmp; /* db_ij */
+ v3_scale(&force,&(exchange->dzeta_ji),f_a*db);
+ v3_scale(&temp,dist_ij,df_a*b);
+ v3_add(&force,&force,&temp);
+ v3_scale(&force,&force,f_c);
+ }
+ v3_scale(&temp,dist_ij,df_c*b*f_a);
+ v3_add(&force,&force,&temp);
+ v3_scale(&force,&force,-0.5);
+
+ /* add force */
+ v3_add(&(ai->f),&(ai->f),&force);
+
+ /* virial - plus sign, as dist_ij = - dist_ji - (really??) */
+// TEST ... with a minus instead
+ ai->virial.xx-=force.x*dist_ij->x;
+ ai->virial.yy-=force.y*dist_ij->y;
+ ai->virial.zz-=force.z*dist_ij->z;
+ ai->virial.xy-=force.x*dist_ij->y;
+ ai->virial.xz-=force.x*dist_ij->z;
+ ai->virial.yz-=force.y*dist_ij->z;
+
+#ifdef DEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVji (3bp) contrib:\n");
+ printf("%f | %f\n",force.x,ai->f.x);
+ printf("%f | %f\n",force.y,ai->f.y);
+ printf("%f | %f\n",force.z,ai->f.z);
+}
+#endif
+#ifdef VDEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVji (3bp) contrib:\n");
+ printf("%f | %f\n",force.x*dist_ij->x,ai->virial.xx);
+ printf("%f | %f\n",force.y*dist_ij->y,ai->virial.yy);
+ printf("%f | %f\n",force.z*dist_ij->z,ai->virial.zz);
+}
+#endif
+
+ 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 temp1,temp2;
+ t_3dvec *dzeta;
+ double R,S,S2,s_r;
+ double B,mu;
+ double d_ij,d_ik,d_jk,d_ij2,d_ik2,d_jk2;
+ double rr,dd;
+ double f_c,df_c;
+ double f_c_ik,df_c_ik,arg;
+ double f_c_jk;
+ double n,c,d,h;
+ double c2,d2,c2d2;
+ double cos_theta,d_costheta1,d_costheta2;
+ double h_cos,d2_h_cos2;
+ double frac,g,zeta,chi;
+ double tmp;
+ int brand;
+
+ params=moldyn->pot3b_params;
+ exchange=&(params->exchange);
+
+ if(!(exchange->run3bp))
+ return 0;
+
+ /*
+ * calc of 3bp contribution of V_ij and dV_ij/ji/jk &
+ * 2bp contribution of dV_jk
+ *
+ * for Vij and dV_ij we still need:
+ * - b_ij, db_ij (zeta_ij)
+ * - f_c_ik, df_c_ik, constants_i, cos_theta_ijk, d_costheta_ijk
+ *
+ * for dV_ji we still need:
+ * - b_ji, db_ji (zeta_ji)
+ * - f_c_jk, d_c_jk, constants_j, cos_theta_jik, d_costheta_jik
+ *
+ * for dV_jk we need:
+ * - f_c_jk
+ * - f_a_jk
+ * - db_jk (zeta_jk)
+ * - f_c_ji, df_c_ji, constants_j, cos_theta_jki, d_costheta_jki
+ *
+ */
+
+ /*
+ * get exchange data
+ */
+
+ /* dist_ij, d_ij - this is < S_ij ! */
+ dist_ij=exchange->dist_ij;
+ d_ij=exchange->d_ij;
+ d_ij2=exchange->d_ij2;
+
+ /* f_c_ij, df_c_ij (same for ji) */
+ f_c=exchange->f_c;
+ df_c=exchange->df_c;
+
+ /*
+ * calculate unknown values now ...
+ */
+
+ /* V_ij and dV_ij stuff (in b_ij there is f_c_ik) */
+
+ /* dist_ik, d_ik */
+ v3_sub(&dist_ik,&(ak->r),&(ai->r));
+ if(bc) check_per_bound(moldyn,&dist_ik);
+ d_ik2=v3_absolute_square(&dist_ik);
+
+ /* ik constants */
+ brand=ai->brand;
+ if(brand==ak->brand) {
+ R=params->R[brand];
+ S=params->S[brand];
+ S2=params->S2[brand];
+ }
+ else {
+ R=params->Rmixed;
+ S=params->Smixed;
+ S2=params->S2mixed;
+ }
+
+ /* zeta_ij/dzeta_ij contribution only for d_ik < S */
+ if(d_ik2<S2) {
+
+ /* now we need d_ik */
+ d_ik=sqrt(d_ik2);
+
+ /* get constants_i from exchange data */
+ n=*(exchange->n_i);
+ c=*(exchange->c_i);
+ d=*(exchange->d_i);
+ h=*(exchange->h_i);
+ c2=exchange->ci2;
+ d2=exchange->di2;
+ c2d2=exchange->ci2di2;
+
+ /* cosine of theta_ijk by scalaproduct */
+ rr=v3_scalar_product(&dist_ij,&dist_ik);
+ dd=d_ij*d_ik;
+ cos_theta=rr/dd;
+
+ /* d_costheta */
+ tmp=1.0/dd;
+ d_costheta1=cos_theta/d_ij2-tmp;
+ d_costheta2=cos_theta/d_ik2-tmp;
+
+ /* some usefull values */
+ h_cos=(h-cos_theta);
+ d2_h_cos2=d2+(h_cos*h_cos);
+ frac=c2/(d2_h_cos2);
+
+ /* g(cos_theta) */
+ g=1.0+c2d2-frac;
+
+ /* d_costheta_ij and dg(cos_theta) - needed in any case! */
+ v3_scale(&temp1,&dist_ij,d_costheta1);
+ v3_scale(&temp2,&dist_ik,d_costheta2);
+ v3_add(&temp1,&temp1,&temp2);
+ v3_scale(&temp1,&temp1,-2.0*frac*h_cos/d2_h_cos2); /* dg */
+
+ /* f_c_ik & df_c_ik + {d,}zeta contribution */
+ dzeta=&(exchange->dzeta_ij);
+ if(d_ik<R) {
+ /* {d,}f_c_ik */
+ // => f_c_ik=1.0;
+ // => df_c_ik=0.0; of course we do not set this!
+
+ /* zeta_ij */
+ exchange->zeta_ij+=g;
+
+ /* dzeta_ij */
+ v3_add(dzeta,dzeta,&temp1);
+ }
+ else {
+ /* {d,}f_c_ik */
+ 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));
+
+ /* zeta_ij */
+ exchange->zeta_ij+=f_c_ik*g;
+
+ /* dzeta_ij */
+ v3_scale(&temp1,&temp1,f_c_ik);
+ v3_scale(&temp2,&dist_ik,g*df_c_ik);
+ v3_add(&temp1,&temp1,&temp2);
+ v3_add(dzeta,dzeta,&temp1);
+ }
+ }
+
+ /* dV_ji stuff (in b_ji there is f_c_jk) + dV_jk stuff! */
+
+ /* dist_jk, d_jk */
+ v3_sub(&dist_jk,&(ak->r),&(aj->r));
+ if(bc) check_per_bound(moldyn,&dist_jk);
+ d_jk2=v3_absolute_square(&dist_jk);
+
+ /* jk constants */
+ brand=aj->brand;
+ if(brand==ak->brand) {
+ R=params->R[brand];
+ S=params->S[brand];
+ S2=params->S2[brand];
+ B=params->B[brand];
+ mu=params->mu[brand];
+ chi=1.0;
+ }
+ else {
+ R=params->Rmixed;
+ S=params->Smixed;
+ S2=params->S2mixed;
+ B=params->Bmixed;
+ mu=params->mu_m;
+ chi=params->chi;
+ }
+
+ /* zeta_ji/dzeta_ji contribution only for d_jk < S_jk */
+ if(d_jk2<S2) {
+
+ /* now we need d_ik */
+ d_jk=sqrt(d_jk2);
+
+ /* constants_j from exchange data */
+ n=*(exchange->n_j);
+ c=*(exchange->c_j);
+ d=*(exchange->d_j);
+ h=*(exchange->h_j);
+ c2=exchange->cj2;
+ d2=exchange->dj2;
+ c2d2=exchange->cj2dj2;
+
+ /* cosine of theta_jik by scalaproduct */
+ rr=-v3_scalar_product(&dist_ij,&dist_jk); /* -1, as ij -> ji */
+ dd=d_ij*d_jk;
+ cos_theta=rr/dd;
+
+ /* d_costheta */
+ d_costheta1=1.0/dd;
+ d_costheta2=cos_theta/d_ij2;
+
+ /* some usefull values */
+ h_cos=(h-cos_theta);
+ d2_h_cos2=d2+(h_cos*h_cos);
+ frac=c2/(d2_h_cos2);
+
+ /* g(cos_theta) */
+ g=1.0+c2d2-frac;
+
+ /* d_costheta_jik and dg(cos_theta) - needed in any case! */
+ v3_scale(&temp1,&dist_jk,d_costheta1);
+ v3_scale(&temp2,&dist_ij,-d_costheta2); /* ji -> ij => -1 */
+ //v3_add(&temp1,&temp1,&temp2);
+ v3_sub(&temp1,&temp1,&temp2); /* there is a minus! */
+ v3_scale(&temp1,&temp1,-2.0*frac*h_cos/d2_h_cos2); /* dg */
+
+ /* store dg in temp2 and use it for dVjk later */
+ v3_copy(&temp2,&temp1);
+
+ /* f_c_jk + {d,}zeta contribution (df_c_jk = 0) */
+ dzeta=&(exchange->dzeta_ji);
+ if(d_jk<R) {
+ /* f_c_jk */
+ f_c_jk=1.0;
+
+ /* zeta_ji */
+ exchange->zeta_ji+=g;
+
+ /* dzeta_ji */
+ v3_add(dzeta,dzeta,&temp1);
+ }
+ else {
+ /* f_c_jk */
+ s_r=S-R;
+ arg=M_PI*(d_jk-R)/s_r;
+ f_c_jk=0.5+0.5*cos(arg);
+
+ /* zeta_ji */
+ exchange->zeta_ji+=f_c_jk*g;
+
+ /* dzeta_ji */
+ v3_scale(&temp1,&temp1,f_c_jk);
+ v3_add(dzeta,dzeta,&temp1);
+ }
+
+ /* dV_jk stuff | add force contribution on atom i immediately */
+ if(exchange->d_ij_between_rs) {
+ zeta=f_c*g;
+ v3_scale(&temp1,&temp2,f_c);
+ v3_scale(&temp2,&dist_ij,df_c*g);
+ v3_add(&temp2,&temp2,&temp1); /* -> dzeta_jk in temp2 */
+ }
+ else {
+ zeta=g;
+ // dzeta_jk is simply dg, which is stored in temp2
+ }
+ /* betajnj * zeta_jk ^ nj-1 */
+ tmp=exchange->betajnj*pow(zeta,(n-1.0));
+ tmp=-chi/2.0*pow((1+tmp*zeta),(-1.0/(2.0*n)-1))*tmp;
+ v3_scale(&temp2,&temp2,tmp*B*exp(-mu*d_jk)*f_c_jk*0.5);
+ v3_add(&(ai->f),&(ai->f),&temp2); /* -1 skipped in f_a calc ^ */
+ /* scaled with 0.5 ^ */
+
+ /* virial */
+ ai->virial.xx-=temp2.x*dist_jk.x;
+ ai->virial.yy-=temp2.y*dist_jk.y;
+ ai->virial.zz-=temp2.z*dist_jk.z;
+ ai->virial.xy-=temp2.x*dist_jk.y;
+ ai->virial.xz-=temp2.x*dist_jk.z;
+ ai->virial.yz-=temp2.y*dist_jk.z;
+
+#ifdef DEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVjk (3bp) contrib:\n");
+ printf("%f | %f\n",temp2.x,ai->f.x);
+ printf("%f | %f\n",temp2.y,ai->f.y);
+ printf("%f | %f\n",temp2.z,ai->f.z);
+}
+#endif
+#ifdef VDEBUG
+if(ai==&(moldyn->atom[0])) {
+ printf("dVjk (3bp) contrib:\n");
+ printf("%f | %f\n",temp2.x*dist_jk.x,ai->virial.xx);
+ printf("%f | %f\n",temp2.y*dist_jk.y,ai->virial.yy);
+ printf("%f | %f\n",temp2.z*dist_jk.z,ai->virial.zz);
+}
+#endif
+
+ }
+
+ return 0;
+}
+
+
+/*
+ * debugging / critical check functions
+ */
+
+int moldyn_bc_check(t_moldyn *moldyn) {
+
+ t_atom *atom;
+ t_3dvec *dim;
+ int i;
+ double x;
+ u8 byte;
+ int j,k;
+
+ atom=moldyn->atom;
+ dim=&(moldyn->dim);
+ x=dim->x/2;
+
+ for(i=0;i<moldyn->count;i++) {
+ if(atom[i].r.x>=dim->x/2||-atom[i].r.x>dim->x/2) {
+ printf("FATAL: atom %d: x: %.20f (%.20f)\n",
+ i,atom[i].r.x,dim->x/2);
+ printf("diagnostic:\n");
+ printf("-----------\natom.r.x:\n");
+ for(j=0;j<8;j++) {
+ memcpy(&byte,(u8 *)(&(atom[i].r.x))+j,1);
+ for(k=0;k<8;k++)
+ printf("%d%c",
+ ((byte)&(1<<k))?1:0,
+ (k==7)?'\n':'|');
+ }
+ printf("---------------\nx=dim.x/2:\n");
+ for(j=0;j<8;j++) {
+ memcpy(&byte,(u8 *)(&x)+j,1);
+ for(k=0;k<8;k++)
+ printf("%d%c",
+ ((byte)&(1<<k))?1:0,
+ (k==7)?'\n':'|');
+ }
+ if(atom[i].r.x==x) printf("the same!\n");
+ else printf("different!\n");
+ }
+ if(atom[i].r.y>=dim->y/2||-atom[i].r.y>dim->y/2)
+ printf("FATAL: atom %d: y: %.20f (%.20f)\n",
+ i,atom[i].r.y,dim->y/2);
+ if(atom[i].r.z>=dim->z/2||-atom[i].r.z>dim->z/2)
+ printf("FATAL: atom %d: z: %.20f (%.20f)\n",
+ i,atom[i].r.z,dim->z/2);
+ }
+
+ return 0;
+}