+ 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,u8 vol) {
+
+ t_linkcell *lc;
+#ifndef LOWMEM_LISTS
+ int i;
+#endif
+
+ 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;
+
+#ifdef STATIC_LISTS
+ lc->subcell=malloc(lc->cells*sizeof(int*));
+#elif LOWMEM_LISTS
+ lc->subcell=malloc(sizeof(t_lowmem_list));
+#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! (%d)\n",
+ lc->cells);
+
+ if(vol) {
+#ifdef STATIC_LISTS
+ printf("[moldyn] initializing 'static' linked cells (%d)\n",
+ lc->cells);
+#elif LOWMEM_LISTS
+ printf("[moldyn] initializing 'lowmem' 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);
+ */
+ }
+#elif LOWMEM_LISTS
+ lc->subcell->head=malloc(lc->cells*sizeof(int));
+ if(lc->subcell->head==NULL) {
+ perror("[moldyn] head init (malloc)");
+ return -1;
+ }
+ lc->subcell->list=malloc(moldyn->count*sizeof(int));
+ if(lc->subcell->list==NULL) {
+ perror("[moldyn] list init (malloc)");
+ return -1;
+ }
+#else
+ for(i=0;i<lc->cells;i++)
+ list_init_f(&(lc->subcell[i]));
+#endif
+
+ /* update the list */
+ link_cell_update(moldyn);
+
+ return 0;
+}
+
+int link_cell_update(t_moldyn *moldyn) {
+
+ int count,i,j,k;
+ int nx,nxy;
+ t_atom *atom;
+ t_linkcell *lc;
+#ifdef STATIC_LISTS
+ int p;
+#elif LOWMEM_LISTS
+ int p;
+#endif
+
+ atom=moldyn->atom;
+ lc=&(moldyn->lc);
+
+ nx=lc->nx;
+ nxy=nx*lc->ny;
+
+ for(i=0;i<lc->cells;i++)
+#ifdef STATIC_LISTS
+ memset(lc->subcell[i],-1,(MAX_ATOMS_PER_LIST+1)*sizeof(int));
+#elif LOWMEM_LISTS
+ lc->subcell->head[i]=-1;
+#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*nxy][p]!=-1)
+ p++;
+
+ if(p>=MAX_ATOMS_PER_LIST) {
+ printf("[moldyn] FATAL: amount of atoms too high!\n");
+ return -1;
+ }
+
+ lc->subcell[i+j*nx+k*nxy][p]=count;
+#elif LOWMEM_LISTS
+ p=i+j*nx+k*nxy;
+ lc->subcell->list[count]=lc->subcell->head[p];
+ lc->subcell->head[p]=count;
+#else
+ list_add_immediate_f(&(lc->subcell[i+j*nx+k*nxy]),
+ &(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,
+#ifdef STATIC_LISTS
+ int **cell
+#elif LOWMEM_LISTS
+ int *cell
+#else
+ t_list *cell
+#endif
+ ) {
+
+ 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;
+
+ if(i>=nx||j>=ny||k>=nz)
+ printf("[moldyn] WARNING: lcni %d/%d %d/%d %d/%d\n",
+ i,nx,j,ny,k,nz);
+
+#ifndef LOWMEM_LISTS
+ cell[0]=lc->subcell[i+j*nx+k*a];
+#else
+ cell[0]=lc->subcell->head[i+j*nx+k*a];
+#endif
+ 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) {
+#ifndef LOWMEM_LISTS
+ cell[--count2]=lc->subcell[x+y*nx+z*a];
+#else
+ cell[--count2]=lc->subcell->head[x+y*nx+z*a];
+#endif
+
+ }
+ else {
+#ifndef LOWMEM_LISTS
+ cell[count1++]=lc->subcell[x+y*nx+z*a];
+#else
+ cell[count1++]=lc->subcell->head[x+y*nx+z*a];
+#endif
+ }
+ }
+ }
+ }
+
+ lc->dnlc=count1;
+
+ return count1;
+}
+
+int link_cell_shutdown(t_moldyn *moldyn) {
+
+#ifndef LOWMEM_LISTS
+ int i;
+#endif
+ t_linkcell *lc;
+
+ lc=&(moldyn->lc);
+
+#if LOWMEM_LISTS
+ free(lc->subcell->head);
+ free(lc->subcell->list);
+
+#else
+
+ 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
+ }
+#endif
+
+ 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,p,t,a;
+ t_3dvec momentum;
+ t_moldyn_schedule *sched;
+ t_atom *atom;
+ int fd;
+ char dir[128];
+ double ds;
+ double energy_scale;
+ struct timeval t1,t2;
+ //double tp;
+
+#ifdef VISUAL_THREAD
+ u8 first,change;
+ pthread_t io_thread;
+ int ret;
+ t_moldyn md_copy;
+ t_atom *atom_copy;
+
+ first=1;
+ change=0;
+#endif
+
+ sched=&(moldyn->schedule);
+ atom=moldyn->atom;
+
+ /* initialize linked cell method */
+ link_cell_init(moldyn,VERBOSE);
+
+ /* logging & visualization */
+ e=moldyn->ewrite;
+ m=moldyn->mwrite;
+ s=moldyn->swrite;
+ v=moldyn->vwrite;
+ a=moldyn->awrite;
+ p=moldyn->pwrite;
+ t=moldyn->twrite;
+
+ /* sqaure of some variables */
+ moldyn->tau_square=moldyn->tau*moldyn->tau;
+
+ /* get current time */
+ gettimeofday(&t1,NULL);
+
+ /* calculate initial forces */
+ potential_force_calc(moldyn);
+#ifdef DEBUG
+//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");
+ 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");
+ if(moldyn->count) {
+ 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 */
+ // should have right values!
+ //moldyn->time=0.0;
+ //moldyn->total_steps=0;
+
+ /* debugging, ignore */
+ moldyn->debug=0;
+
+ /* zero & init moldyn copy */
+#ifdef VISUAL_THREAD
+ memset(&md_copy,0,sizeof(t_moldyn));
+ atom_copy=malloc(moldyn->count*sizeof(t_atom));
+ if(atom_copy==NULL) {
+ perror("[moldyn] malloc atom copy (init)");
+ return -1;
+ }
+#endif
+
+#ifdef PTHREADS
+ printf("##################\n");
+ printf("# USING PTHREADS #\n");
+ printf("##################\n");
+#endif
+ /* tell the world */
+ printf("[moldyn] integration start, go get a coffee ...\n");
+
+ /* executing the schedule */
+ sched->count=0;
+ while(sched->count<sched->total_sched) {
+
+ /* 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];
+
+ /* energy scaling factor (might change!) */
+ energy_scale=moldyn->count*EV;
+
+ /* integration according to schedule */
+
+ for(i=0;i<moldyn->time_steps;i++) {
+
+ /* integration step */
+ moldyn->integrate(moldyn);
+
+ /* calculate kinetic energy, temperature and pressure */
+ e_kin_calc(moldyn);
+ temperature_calc(moldyn);
+ virial_sum(moldyn);
+ pressure_calc(moldyn);
+#ifdef PDEBUG
+ thermodynamic_pressure_calc(moldyn);
+ printf("\n\nDEBUG: numeric pressure calc: %f\n\n",
+ moldyn->tp/BAR);
+#endif
+
+ /* calculate fluctuations + averages */
+ average_and_fluctuation_calc(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);
+
+ /* check for log & visualization */
+ if(e) {
+ if(!(moldyn->total_steps%e))
+ dprintf(moldyn->efd,
+ "%f %f %f %f %f %f\n",
+ moldyn->time,moldyn->ekin/energy_scale,
+ moldyn->energy/energy_scale,
+ get_total_energy(moldyn)/energy_scale,
+ moldyn->ekin/EV,moldyn->energy/EV);
+ }
+ if(m) {
+ if(!(moldyn->total_steps%m)) {
+ momentum=get_total_p(moldyn);
+ dprintf(moldyn->mfd,
+ "%f %f %f %f %f\n",moldyn->time,
+ momentum.x,momentum.y,momentum.z,
+ v3_norm(&momentum));
+ }
+ }
+ if(p) {
+ if(!(moldyn->total_steps%p)) {
+ dprintf(moldyn->pfd,
+ "%f %f %f %f %f %f %f\n",moldyn->time,
+ moldyn->p/BAR,moldyn->p_avg/BAR,
+ moldyn->p/BAR,moldyn->p_avg/BAR,
+ moldyn->tp/BAR,moldyn->tp_avg/BAR);
+ }
+ }
+ if(t) {
+ if(!(moldyn->total_steps%t)) {
+ dprintf(moldyn->tfd,
+ "%f %f %f\n",
+ moldyn->time,moldyn->t,moldyn->t_avg);
+ }
+ }
+ if(v) {
+ if(!(moldyn->total_steps%v)) {
+ dprintf(moldyn->vfd,
+ "%f %f %f %f %f\n",moldyn->time,
+ moldyn->volume,
+ moldyn->dim.x,
+ moldyn->dim.y,
+ moldyn->dim.z);
+ }
+ }
+ if(s) {
+ if(!(moldyn->total_steps%s)) {
+ snprintf(dir,128,"%s/s-%08.f.save",
+ moldyn->vlsdir,moldyn->time);
+ fd=open(dir,O_WRONLY|O_TRUNC|O_CREAT,
+ S_IRUSR|S_IWUSR);
+ 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(a) {
+ if(!(moldyn->total_steps%a)) {
+#ifdef VISUAL_THREAD
+ /* check whether thread has not terminated yet */
+ if(!first) {
+ ret=pthread_join(io_thread,NULL);
+ }
+ first=0;
+ /* prepare and start thread */
+ if(moldyn->count!=md_copy.count) {
+ free(atom_copy);
+ change=1;
+ }
+ memcpy(&md_copy,moldyn,sizeof(t_moldyn));
+ if(change) {
+ atom_copy=malloc(moldyn->count*sizeof(t_atom));
+ if(atom_copy==NULL) {
+ perror("[moldyn] malloc atom copy (change)");
+ return -1;
+ }
+ }
+ md_copy.atom=atom_copy;
+ memcpy(atom_copy,moldyn->atom,moldyn->count*sizeof(t_atom));
+ change=0;
+ ret=pthread_create(&io_thread,NULL,visual_atoms,&md_copy);
+ if(ret) {
+ perror("[moldyn] create visual atoms thread\n");
+ return -1;
+ }
+#else
+ visual_atoms(moldyn);
+#endif
+ }
+ }
+
+ /* display progress */
+#ifndef PDEBUG
+ if(!(i%10)) {
+#endif
+ /* get current time */
+ gettimeofday(&t2,NULL);
+
+printf("sched:%d, steps:%d/%d, T:%4.1f/%4.1f P:%4.1f/%4.1f V:%6.1f (%d)\n",
+ sched->count,i,moldyn->total_steps,
+ moldyn->t,moldyn->t_avg,
+#ifndef PDEBUG
+ moldyn->p/BAR,moldyn->p_avg/BAR,
+#else
+ moldyn->p/BAR,(moldyn->p-2.0*moldyn->ekin/(3.0*moldyn->volume))/BAR,
+#endif
+ moldyn->volume,
+ (int)(t2.tv_sec-t1.tv_sec));
+
+ fflush(stdout);
+
+ /* copy over time */
+ t1=t2;
+#ifndef PDEBUG
+ }
+#endif
+
+ /* increase absolute time */
+ moldyn->time+=moldyn->tau;
+ moldyn->total_steps+=1;
+
+ }
+
+ /* check for hooks */
+ if(sched->hook) {
+ printf("\n ## schedule hook %d start ##\n",
+ sched->count);
+ sched->hook(moldyn,sched->hook_params);
+ printf(" ## schedule hook end ##\n");
+ }
+
+ /* increase the schedule counter */
+ sched->count+=1;
+
+ }
+
+ /* writing a final save file! */
+ if(s) {
+ snprintf(dir,128,"%s/s-final.save",moldyn->vlsdir);
+ fd=open(dir,O_WRONLY|O_TRUNC|O_CREAT,S_IRUSR|S_IWUSR);
+ 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);
+ }
+ /* writing a final visual file! */
+ if(a)
+ visual_atoms(moldyn);
+
+ return 0;
+}
+
+/* basis trafo */
+
+#define FORWARD 0
+#define BACKWARD 1
+
+int basis_trafo(t_3dvec *r,u8 dir,double z,double x) {
+
+ t_3dvec tmp;
+
+ if(dir==FORWARD) {
+ if(z!=0.0) {
+ v3_copy(&tmp,r);
+ r->x=cos(z)*tmp.x-sin(z)*tmp.y;
+ r->y=sin(z)*tmp.x+cos(z)*tmp.y;
+ }
+ if(x!=0.0) {
+ v3_copy(&tmp,r);
+ r->y=cos(x)*tmp.y-sin(x)*tmp.z;
+ r->z=sin(x)*tmp.y+cos(x)*tmp.z;
+ }
+ }
+ else {
+ if(x!=0.0) {
+ v3_copy(&tmp,r);
+ r->y=cos(-x)*tmp.y-sin(-x)*tmp.z;
+ r->z=sin(-x)*tmp.y+cos(-x)*tmp.z;
+ }
+ if(z!=0.0) {
+ v3_copy(&tmp,r);
+ r->x=cos(-z)*tmp.x-sin(-z)*tmp.y;
+ r->y=sin(-z)*tmp.x+cos(-z)*tmp.y;
+ }
+ }
+
+ 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++) {
+
+ /* check whether fixed atom */
+ if(atom[i].attr&ATOM_ATTR_FP)
+ continue;
+
+ /* new positions */
+ h=0.5/atom[i].mass;
+
+ /* constraint relaxation */
+ if(crtt) {
+ // forces
+ basis_trafo(&(atom[i].f),FORWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ if(constraints[3*i])
+ atom[i].f.x=0;
+ if(constraints[3*i+1])
+ atom[i].f.y=0;
+ if(constraints[3*i+2])
+ atom[i].f.z=0;
+ basis_trafo(&(atom[i].f),BACKWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ // velocities
+ basis_trafo(&(atom[i].v),FORWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ if(constraints[3*i])
+ atom[i].v.x=0;
+ if(constraints[3*i+1])
+ atom[i].v.y=0;
+ if(constraints[3*i+2])
+ atom[i].v.z=0;
+ basis_trafo(&(atom[i].v),BACKWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ }
+
+#ifndef QUENCH
+ v3_scale(&delta,&(atom[i].v),tau);
+ v3_add(&(atom[i].r),&(atom[i].r),&delta);
+#endif
+ v3_scale(&delta,&(atom[i].f),h*tau_square);
+ v3_add(&(atom[i].r),&(atom[i].r),&delta);
+ //check_per_bound_and_care_for_pbc(moldyn,&(atom[i]));
+ 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);
+ }
+
+ /* criticial check */
+ moldyn_bc_check(moldyn);
+
+ /* neighbour list update */
+ link_cell_update(moldyn);
+
+ /* forces depending on chosen potential */
+#ifndef ALBE_FAST
+ // if albe, use albe force calc routine
+ //if(moldyn->func3b_j1==albe_mult_3bp_j1)
+ // albe_potential_force_calc(moldyn);
+ //else
+ potential_force_calc(moldyn);
+#else
+ albe_potential_force_calc(moldyn);
+#endif
+
+ for(i=0;i<count;i++) {
+ /* check whether fixed atom */
+ if(atom[i].attr&ATOM_ATTR_FP)
+ continue;
+
+ /* constraint relaxation */
+ if(crtt) {
+ // forces
+ basis_trafo(&(atom[i].f),FORWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ if(constraints[3*i])
+ atom[i].f.x=0;
+ if(constraints[3*i+1])
+ atom[i].f.y=0;
+ if(constraints[3*i+2])
+ atom[i].f.z=0;
+ basis_trafo(&(atom[i].f),BACKWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ // velocities
+ basis_trafo(&(atom[i].v),FORWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ if(constraints[3*i])
+ atom[i].v.x=0;
+ if(constraints[3*i+1])
+ atom[i].v.y=0;
+ if(constraints[3*i+2])
+ atom[i].v.z=0;
+ basis_trafo(&(atom[i].v),BACKWARD,
+ trafo_angle[2*i],trafo_angle[2*i+1]);
+ }
+
+ /* 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;
+#ifdef STATIC_LISTS
+ int *neighbour_i[27];
+ int p,q;
+ t_atom *atom;
+#elif LOWMEM_LISTS
+ int neighbour_i[27];
+ int p,q;
+#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;
+
+ /* reset global virial */
+ memset(&(moldyn->gvir),0,sizeof(t_virial));
+
+ /* reset force, site energy and virial of every atom */
+#ifdef PARALLEL
+ i=omp_get_thread_num();
+ #pragma omp parallel for private(virial)
+#endif
+ 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 */
+
+ /* first (and only) loop over atoms i */
+ for(i=0;i<count;i++) {