2 * moldyn.c - molecular dynamics library main file
4 * author: Frank Zirkelbach <frank.zirkelbach@physik.uni-augsburg.de>
12 #include <sys/types.h>
20 int moldyn_init(t_moldyn *moldyn,int argc,char **argv) {
22 memset(moldyn,0,sizeof(t_moldyn));
24 rand_init(&(moldyn->random),NULL,1);
25 moldyn->random.status|=RAND_STAT_VERBOSE;
30 int moldyn_shutdown(t_moldyn *moldyn) {
32 printf("[moldyn] shutdown\n");
33 moldyn_log_shutdown(moldyn);
34 link_cell_shutdown(moldyn);
35 rand_close(&(moldyn->random));
41 int set_int_alg(t_moldyn *moldyn,u8 algo) {
44 case MOLDYN_INTEGRATE_VERLET:
45 moldyn->integrate=velocity_verlet;
48 printf("unknown integration algorithm: %02x\n",algo);
55 int set_cutoff(t_moldyn *moldyn,double cutoff) {
57 moldyn->cutoff=cutoff;
62 int set_temperature(t_moldyn *moldyn,double t_ref) {
69 int set_pressure(t_moldyn *moldyn,double p_ref) {
76 int set_pt_scale(t_moldyn *moldyn,u8 ptype,double ptc,u8 ttype,double ttc) {
78 moldyn->pt_scale=(ptype|ttype);
85 int set_dim(t_moldyn *moldyn,double x,double y,double z,u8 visualize) {
99 printf("[moldyn] dimensions in A and A^3 respectively:\n");
100 printf(" x: %f\n",moldyn->dim.x);
101 printf(" y: %f\n",moldyn->dim.y);
102 printf(" z: %f\n",moldyn->dim.z);
103 printf(" volume: %f\n",moldyn->volume);
104 printf(" visualize simulation box: %s\n",visualize?"on":"off");
109 int set_nn_dist(t_moldyn *moldyn,double dist) {
116 int set_pbc(t_moldyn *moldyn,u8 x,u8 y,u8 z) {
119 moldyn->status|=MOLDYN_STAT_PBX;
122 moldyn->status|=MOLDYN_STAT_PBY;
125 moldyn->status|=MOLDYN_STAT_PBZ;
130 int set_potential1b(t_moldyn *moldyn,pf_func1b func,void *params) {
133 moldyn->pot1b_params=params;
138 int set_potential2b(t_moldyn *moldyn,pf_func2b func,void *params) {
141 moldyn->pot2b_params=params;
146 int set_potential2b_post(t_moldyn *moldyn,pf_func2b_post func,void *params) {
148 moldyn->func2b_post=func;
149 moldyn->pot2b_params=params;
154 int set_potential3b(t_moldyn *moldyn,pf_func3b func,void *params) {
157 moldyn->pot3b_params=params;
162 int moldyn_set_log_dir(t_moldyn *moldyn,char *dir) {
164 strncpy(moldyn->vlsdir,dir,127);
169 int moldyn_set_log(t_moldyn *moldyn,u8 type,int timer) {
175 case LOG_TOTAL_ENERGY:
176 moldyn->ewrite=timer;
177 snprintf(filename,127,"%s/energy",moldyn->vlsdir);
178 moldyn->efd=open(filename,
179 O_WRONLY|O_CREAT|O_EXCL,
182 perror("[moldyn] energy log fd open");
185 dprintf(moldyn->efd,"# total energy log file\n");
187 case LOG_TOTAL_MOMENTUM:
188 moldyn->mwrite=timer;
189 snprintf(filename,127,"%s/momentum",moldyn->vlsdir);
190 moldyn->mfd=open(filename,
191 O_WRONLY|O_CREAT|O_EXCL,
194 perror("[moldyn] momentum log fd open");
197 dprintf(moldyn->efd,"# total momentum log file\n");
200 moldyn->swrite=timer;
203 moldyn->vwrite=timer;
204 ret=visual_init(&(moldyn->vis),moldyn->vlsdir);
206 printf("[moldyn] visual init failure\n");
211 printf("[moldyn] unknown log mechanism: %02x\n",type);
218 int moldyn_log_shutdown(t_moldyn *moldyn) {
220 printf("[moldyn] log shutdown\n");
221 if(moldyn->efd) close(moldyn->efd);
222 if(moldyn->mfd) close(moldyn->mfd);
223 if(&(moldyn->vis)) visual_tini(&(moldyn->vis));
229 * creating lattice functions
232 int create_lattice(t_moldyn *moldyn,u8 type,double lc,int element,double mass,
233 u8 attr,u8 brand,int a,int b,int c) {
244 /* how many atoms do we expect */
245 if(type==FCC) new*=4;
246 if(type==DIAMOND) new*=8;
248 /* allocate space for atoms */
249 ptr=realloc(moldyn->atom,(count+new)*sizeof(t_atom));
251 perror("[moldyn] realloc (create lattice)");
255 atom=&(moldyn->atom[count]);
261 ret=fcc_init(a,b,c,lc,atom,&origin);
264 ret=diamond_init(a,b,c,lc,atom,&origin);
267 printf("unknown lattice type (%02x)\n",type);
273 printf("[moldyn] creating lattice failed\n");
274 printf(" amount of atoms\n");
275 printf(" - expected: %d\n",new);
276 printf(" - created: %d\n",ret);
281 printf("[moldyn] created lattice with %d atoms\n",new);
283 for(ret=0;ret<new;ret++) {
284 atom[ret].element=element;
287 atom[ret].brand=brand;
288 atom[ret].tag=count+ret;
289 check_per_bound(moldyn,&(atom[ret].r));
295 /* fcc lattice init */
296 int fcc_init(int a,int b,int c,double lc,t_atom *atom,t_3dvec *origin) {
309 if(origin) v3_copy(&o,origin);
312 /* construct the basis */
315 if(i!=j) help[j]=0.5*lc;
318 v3_set(&basis[i],help);
324 /* fill up the room */
331 v3_copy(&(atom[count].r),&r);
332 atom[count].element=1;
335 v3_add(&n,&r,&basis[i]);
339 v3_copy(&(atom[count].r),&n);
350 /* coordinate transformation */
356 v3_sub(&(atom[i].r),&(atom[i].r),&n);
361 int diamond_init(int a,int b,int c,double lc,t_atom *atom,t_3dvec *origin) {
366 count=fcc_init(a,b,c,lc,atom,origin);
372 if(origin) v3_add(&o,&o,origin);
374 count+=fcc_init(a,b,c,lc,&atom[count],&o);
379 int add_atom(t_moldyn *moldyn,int element,double mass,u8 brand,u8 attr,
380 t_3dvec *r,t_3dvec *v) {
387 count=(moldyn->count)++;
389 ptr=realloc(atom,(count+1)*sizeof(t_atom));
391 perror("[moldyn] realloc (add atom)");
399 atom[count].element=element;
400 atom[count].mass=mass;
401 atom[count].brand=brand;
402 atom[count].tag=count;
403 atom[count].attr=attr;
408 int destroy_atoms(t_moldyn *moldyn) {
410 if(moldyn->atom) free(moldyn->atom);
415 int thermal_init(t_moldyn *moldyn,u8 equi_init) {
418 * - gaussian distribution of velocities
419 * - zero total momentum
420 * - velocity scaling (E = 3/2 N k T), E: kinetic energy
425 t_3dvec p_total,delta;
430 random=&(moldyn->random);
432 /* gaussian distribution of velocities */
434 for(i=0;i<moldyn->count;i++) {
435 sigma=sqrt(2.0*K_BOLTZMANN*moldyn->t_ref/atom[i].mass);
437 v=sigma*rand_get_gauss(random);
439 p_total.x+=atom[i].mass*v;
441 v=sigma*rand_get_gauss(random);
443 p_total.y+=atom[i].mass*v;
445 v=sigma*rand_get_gauss(random);
447 p_total.z+=atom[i].mass*v;
450 /* zero total momentum */
451 v3_scale(&p_total,&p_total,1.0/moldyn->count);
452 for(i=0;i<moldyn->count;i++) {
453 v3_scale(&delta,&p_total,1.0/atom[i].mass);
454 v3_sub(&(atom[i].v),&(atom[i].v),&delta);
457 /* velocity scaling */
458 scale_velocity(moldyn,equi_init);
463 int scale_velocity(t_moldyn *moldyn,u8 equi_init) {
473 * - velocity scaling (E = 3/2 N k T), E: kinetic energy
476 /* get kinetic energy / temperature & count involved atoms */
479 for(i=0;i<moldyn->count;i++) {
480 if((equi_init&TRUE)||(atom[i].attr&ATOM_ATTR_HB)) {
481 e+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
485 if(count!=0) moldyn->t=e/(1.5*count*K_BOLTZMANN);
486 else return 0; /* no atoms involved in scaling! */
488 /* (temporary) hack for e,t = 0 */
491 if(moldyn->t_ref!=0.0) {
492 thermal_init(moldyn,equi_init);
496 return 0; /* no scaling needed */
500 /* get scaling factor */
501 scale=moldyn->t_ref/moldyn->t;
505 if(moldyn->pt_scale&T_SCALE_BERENDSEN)
506 scale=1.0+(scale-1.0)/moldyn->t_tc;
509 /* velocity scaling */
510 for(i=0;i<moldyn->count;i++) {
511 if((equi_init&TRUE)||(atom[i].attr&ATOM_ATTR_HB))
512 v3_scale(&(atom[i].v),&(atom[i].v),scale);
518 int scale_volume(t_moldyn *moldyn) {
528 vdim=&(moldyn->vis.dim);
531 for(i=0;i<moldyn->count;i++)
532 virial+=v3_norm(&(atom[i].virial));
534 printf("%f\n",virial);
535 /* get pressure from virial */
536 moldyn->p=moldyn->count*K_BOLTZMANN*moldyn->t-ONE_THIRD*virial;
537 moldyn->p/=moldyn->volume;
538 printf("%f\n",moldyn->p/(ATM));
541 if(moldyn->pt_scale&P_SCALE_BERENDSEN)
542 scale=3*sqrt(1-(moldyn->p_ref-moldyn->p)/moldyn->p_tc);
544 /* should actually never be used */
545 scale=pow(moldyn->p/moldyn->p_ref,1.0/3.0);
547 printf("scale = %f\n",scale);
552 if(vdim->x) vdim->x=dim->x;
553 if(vdim->y) vdim->y=dim->y;
554 if(vdim->z) vdim->z=dim->z;
555 moldyn->volume*=(scale*scale*scale);
557 /* check whether we need a new linkcell init */
558 if((dim->x/moldyn->cutoff!=lc->nx)||
559 (dim->y/moldyn->cutoff!=lc->ny)||
560 (dim->z/moldyn->cutoff!=lc->nx)) {
561 link_cell_shutdown(moldyn);
562 link_cell_init(moldyn);
569 double get_e_kin(t_moldyn *moldyn) {
577 for(i=0;i<moldyn->count;i++)
578 moldyn->ekin+=0.5*atom[i].mass*v3_absolute_square(&(atom[i].v));
583 double get_e_pot(t_moldyn *moldyn) {
585 return moldyn->energy;
588 double update_e_kin(t_moldyn *moldyn) {
590 return(get_e_kin(moldyn));
593 double get_total_energy(t_moldyn *moldyn) {
595 return(moldyn->ekin+moldyn->energy);
598 t_3dvec get_total_p(t_moldyn *moldyn) {
607 for(i=0;i<moldyn->count;i++) {
608 v3_scale(&p,&(atom[i].v),atom[i].mass);
609 v3_add(&p_total,&p_total,&p);
615 double estimate_time_step(t_moldyn *moldyn,double nn_dist) {
619 /* nn_dist is the nearest neighbour distance */
621 tau=(0.05*nn_dist*moldyn->atom[0].mass)/sqrt(3.0*K_BOLTZMANN*moldyn->t);
630 /* linked list / cell method */
632 int link_cell_init(t_moldyn *moldyn) {
639 /* partitioning the md cell */
640 lc->nx=moldyn->dim.x/moldyn->cutoff;
641 lc->x=moldyn->dim.x/lc->nx;
642 lc->ny=moldyn->dim.y/moldyn->cutoff;
643 lc->y=moldyn->dim.y/lc->ny;
644 lc->nz=moldyn->dim.z/moldyn->cutoff;
645 lc->z=moldyn->dim.z/lc->nz;
647 lc->cells=lc->nx*lc->ny*lc->nz;
648 lc->subcell=malloc(lc->cells*sizeof(t_list));
650 printf("[moldyn] initializing linked cells (%d)\n",lc->cells);
652 for(i=0;i<lc->cells;i++)
653 list_init_f(&(lc->subcell[i]));
655 link_cell_update(moldyn);
660 int link_cell_update(t_moldyn *moldyn) {
678 for(i=0;i<lc->cells;i++)
679 list_destroy_f(&(lc->subcell[i]));
681 for(count=0;count<moldyn->count;count++) {
682 i=((atom[count].r.x+(moldyn->dim.x/2))/lc->x);
683 j=((atom[count].r.y+(moldyn->dim.y/2))/lc->y);
684 k=((atom[count].r.z+(moldyn->dim.z/2))/lc->z);
685 list_add_immediate_f(&(moldyn->lc.subcell[i+j*nx+k*nx*ny]),
692 int link_cell_neighbour_index(t_moldyn *moldyn,int i,int j,int k,t_list *cell) {
710 cell[0]=lc->subcell[i+j*nx+k*a];
711 for(ci=-1;ci<=1;ci++) {
718 for(cj=-1;cj<=1;cj++) {
725 for(ck=-1;ck<=1;ck++) {
732 if(!(ci|cj|ck)) continue;
734 cell[--count2]=lc->subcell[x+y*nx+z*a];
737 cell[count1++]=lc->subcell[x+y*nx+z*a];
748 int link_cell_shutdown(t_moldyn *moldyn) {
755 for(i=0;i<lc->nx*lc->ny*lc->nz;i++)
756 list_destroy_f(&(moldyn->lc.subcell[i]));
763 int moldyn_add_schedule(t_moldyn *moldyn,int runs,double tau) {
767 t_moldyn_schedule *schedule;
769 schedule=&(moldyn->schedule);
770 count=++(schedule->content_count);
772 ptr=realloc(moldyn->schedule.runs,count*sizeof(int));
774 perror("[moldyn] realloc (runs)");
777 moldyn->schedule.runs=ptr;
778 moldyn->schedule.runs[count-1]=runs;
780 ptr=realloc(schedule->tau,count*sizeof(double));
782 perror("[moldyn] realloc (tau)");
785 moldyn->schedule.tau=ptr;
786 moldyn->schedule.tau[count-1]=tau;
791 int moldyn_set_schedule_hook(t_moldyn *moldyn,void *hook,void *hook_params) {
793 moldyn->schedule.hook=hook;
794 moldyn->schedule.hook_params=hook_params;
801 * 'integration of newtons equation' - algorithms
805 /* start the integration */
807 int moldyn_integrate(t_moldyn *moldyn) {
810 unsigned int e,m,s,v;
812 t_moldyn_schedule *schedule;
818 schedule=&(moldyn->schedule);
821 /* initialize linked cell method */
822 link_cell_init(moldyn);
824 /* logging & visualization */
830 /* sqaure of some variables */
831 moldyn->tau_square=moldyn->tau*moldyn->tau;
832 moldyn->cutoff_square=moldyn->cutoff*moldyn->cutoff;
834 /* calculate initial forces */
835 potential_force_calc(moldyn);
837 /* some stupid checks before we actually start calculating bullshit */
838 if(moldyn->cutoff>0.5*moldyn->dim.x)
839 printf("[moldyn] warning: cutoff > 0.5 x dim.x\n");
840 if(moldyn->cutoff>0.5*moldyn->dim.y)
841 printf("[moldyn] warning: cutoff > 0.5 x dim.y\n");
842 if(moldyn->cutoff>0.5*moldyn->dim.z)
843 printf("[moldyn] warning: cutoff > 0.5 x dim.z\n");
844 ds=0.5*atom[0].f.x*moldyn->tau_square/atom[0].mass;
845 if(ds>0.05*moldyn->nnd)
846 printf("[moldyn] warning: forces too high / tau too small!\n");
848 /* zero absolute time */
851 /* debugging, ignore */
854 /* executing the schedule */
855 for(sched=0;sched<moldyn->schedule.content_count;sched++) {
857 /* setting amount of runs and finite time step size */
858 moldyn->tau=schedule->tau[sched];
859 moldyn->tau_square=moldyn->tau*moldyn->tau;
860 moldyn->time_steps=schedule->runs[sched];
862 /* integration according to schedule */
864 for(i=0;i<moldyn->time_steps;i++) {
866 /* integration step */
867 moldyn->integrate(moldyn);
870 if(moldyn->pt_scale&(T_SCALE_BERENDSEN|T_SCALE_DIRECT))
871 scale_velocity(moldyn,FALSE);
872 if(moldyn->pt_scale&(P_SCALE_BERENDSEN|P_SCALE_DIRECT))
873 scale_volume(moldyn);
875 /* check for log & visualization */
880 moldyn->time,update_e_kin(moldyn),
882 get_total_energy(moldyn));
886 p=get_total_p(moldyn);
888 "%f %f\n",moldyn->time,v3_norm(&p));
893 snprintf(dir,128,"%s/s-%07.f.save",
894 moldyn->vlsdir,moldyn->time);
895 fd=open(dir,O_WRONLY|O_TRUNC|O_CREAT);
896 if(fd<0) perror("[moldyn] save fd open");
898 write(fd,moldyn,sizeof(t_moldyn));
899 write(fd,moldyn->atom,
900 moldyn->count*sizeof(t_atom));
907 visual_atoms(&(moldyn->vis),moldyn->time,
908 moldyn->atom,moldyn->count);
909 printf("\rsched: %d, steps: %d, debug: %d",
910 sched,i,moldyn->debug);
915 /* increase absolute time */
916 moldyn->time+=moldyn->tau;
920 /* check for hooks */
922 schedule->hook(moldyn,schedule->hook_params);
924 /* get a new info line */
932 /* velocity verlet */
934 int velocity_verlet(t_moldyn *moldyn) {
937 double tau,tau_square;
944 tau_square=moldyn->tau_square;
946 for(i=0;i<count;i++) {
948 v3_scale(&delta,&(atom[i].v),tau);
949 v3_add(&(atom[i].r),&(atom[i].r),&delta);
950 v3_scale(&delta,&(atom[i].f),0.5*tau_square/atom[i].mass);
951 v3_add(&(atom[i].r),&(atom[i].r),&delta);
952 check_per_bound(moldyn,&(atom[i].r));
955 v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
956 v3_add(&(atom[i].v),&(atom[i].v),&delta);
959 /* neighbour list update */
960 link_cell_update(moldyn);
962 /* forces depending on chosen potential */
963 potential_force_calc(moldyn);
965 for(i=0;i<count;i++) {
966 /* again velocities */
967 v3_scale(&delta,&(atom[i].f),0.5*tau/atom[i].mass);
968 v3_add(&(atom[i].v),&(atom[i].v),&delta);
977 * potentials & corresponding forces
981 /* generic potential and force calculation */
983 int potential_force_calc(t_moldyn *moldyn) {
986 t_atom *itom,*jtom,*ktom;
988 t_list neighbour_i[27];
989 t_list neighbour_i2[27];
1001 /* get energy and force of every atom */
1002 for(i=0;i<count;i++) {
1005 v3_zero(&(itom[i].f));
1007 /* reset viral of atom i */
1008 v3_zero(&(itom[i].virial));
1010 /* reset site energy */
1013 /* single particle potential/force */
1014 if(itom[i].attr&ATOM_ATTR_1BP)
1015 moldyn->func1b(moldyn,&(itom[i]));
1017 if(!(itom[i].attr&(ATOM_ATTR_2BP|ATOM_ATTR_3BP)))
1020 /* 2 body pair potential/force */
1022 link_cell_neighbour_index(moldyn,
1023 (itom[i].r.x+moldyn->dim.x/2)/lc->x,
1024 (itom[i].r.y+moldyn->dim.y/2)/lc->y,
1025 (itom[i].r.z+moldyn->dim.z/2)/lc->z,
1032 this=&(neighbour_i[j]);
1035 if(this->start==NULL)
1041 jtom=this->current->data;
1043 if(jtom==&(itom[i]))
1046 if((jtom->attr&ATOM_ATTR_2BP)&
1047 (itom[i].attr&ATOM_ATTR_2BP)) {
1048 moldyn->func2b(moldyn,
1054 /* 3 body potential/force */
1056 if(!(itom[i].attr&ATOM_ATTR_3BP)||
1057 !(jtom->attr&ATOM_ATTR_3BP))
1060 /* copy the neighbour lists */
1061 memcpy(neighbour_i2,neighbour_i,
1064 /* get neighbours of i */
1067 that=&(neighbour_i2[k]);
1070 if(that->start==NULL)
1077 ktom=that->current->data;
1079 if(!(ktom->attr&ATOM_ATTR_3BP))
1085 if(ktom==&(itom[i]))
1088 moldyn->func3b(moldyn,
1094 } while(list_next_f(that)!=\
1099 /* 2bp post function */
1100 if(moldyn->func2b_post) {
1101 moldyn->func2b_post(moldyn,
1106 } while(list_next_f(this)!=L_NO_NEXT_ELEMENT);
1116 * periodic boundayr checking
1119 inline int check_per_bound(t_moldyn *moldyn,t_3dvec *a) {
1130 if(moldyn->status&MOLDYN_STAT_PBX) {
1131 if(a->x>=x) a->x-=dim->x;
1132 else if(-a->x>x) a->x+=dim->x;
1134 if(moldyn->status&MOLDYN_STAT_PBY) {
1135 if(a->y>=y) a->y-=dim->y;
1136 else if(-a->y>y) a->y+=dim->y;
1138 if(moldyn->status&MOLDYN_STAT_PBZ) {
1139 if(a->z>=z) a->z-=dim->z;
1140 else if(-a->z>z) a->z+=dim->z;
1148 * example potentials
1151 /* harmonic oscillator potential and force */
1153 int harmonic_oscillator(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
1155 t_ho_params *params;
1156 t_3dvec force,distance;
1158 double sc,equi_dist;
1160 params=moldyn->pot2b_params;
1161 sc=params->spring_constant;
1162 equi_dist=params->equilibrium_distance;
1164 v3_sub(&distance,&(aj->r),&(ai->r));
1166 if(bc) check_per_bound(moldyn,&distance);
1167 d=v3_norm(&distance);
1168 if(d<=moldyn->cutoff) {
1169 /* energy is 1/2 (d-d0)^2, but we will add this twice ... */
1170 moldyn->energy+=(0.25*sc*(d-equi_dist)*(d-equi_dist));
1171 /* f = -grad E; grad r_ij = -1 1/r_ij distance */
1172 v3_scale(&force,&distance,sc*(1.0-(equi_dist/d)));
1173 v3_add(&(ai->f),&(ai->f),&force);
1179 /* lennard jones potential & force for one sort of atoms */
1181 int lennard_jones(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
1183 t_lj_params *params;
1184 t_3dvec force,distance;
1186 double eps,sig6,sig12;
1188 params=moldyn->pot2b_params;
1189 eps=params->epsilon4;
1190 sig6=params->sigma6;
1191 sig12=params->sigma12;
1193 v3_sub(&distance,&(aj->r),&(ai->r));
1194 if(bc) check_per_bound(moldyn,&distance);
1195 d=v3_absolute_square(&distance); /* 1/r^2 */
1196 if(d<=moldyn->cutoff_square) {
1197 d=1.0/d; /* 1/r^2 */
1200 h1=h2*h2; /* 1/r^12 */
1201 /* energy is eps*..., but we will add this twice ... */
1202 moldyn->energy+=0.5*eps*(sig12*h1-sig6*h2);
1209 v3_scale(&force,&distance,-1.0*d); /* f = - grad E */
1210 v3_add(&(ai->f),&(ai->f),&force);
1217 * tersoff potential & force for 2 sorts of atoms
1220 /* create mixed terms from parameters and set them */
1221 int tersoff_mult_complete_params(t_tersoff_mult_params *p) {
1223 printf("[moldyn] tersoff parameter completion\n");
1224 p->Smixed=sqrt(p->S[0]*p->S[1]);
1225 p->Rmixed=sqrt(p->R[0]*p->R[1]);
1226 p->Amixed=sqrt(p->A[0]*p->A[1]);
1227 p->Bmixed=sqrt(p->B[0]*p->B[1]);
1228 p->lambda_m=0.5*(p->lambda[0]+p->lambda[1]);
1229 p->mu_m=0.5*(p->mu[0]+p->mu[1]);
1231 printf("[moldyn] tersoff mult parameter info:\n");
1232 printf(" S (A) | %f | %f | %f\n",p->S[0],p->S[1],p->Smixed);
1233 printf(" R (A) | %f | %f | %f\n",p->R[0],p->R[1],p->Rmixed);
1234 printf(" A (eV) | %f | %f | %f\n",p->A[0]/EV,p->A[1]/EV,p->Amixed/EV);
1235 printf(" B (eV) | %f | %f | %f\n",p->B[0]/EV,p->B[1]/EV,p->Bmixed/EV);
1236 printf(" lambda | %f | %f | %f\n",p->lambda[0],p->lambda[1],
1238 printf(" mu | %f | %f | %f\n",p->mu[0],p->mu[1],p->mu_m);
1239 printf(" beta | %.10f | %.10f\n",p->beta[0],p->beta[1]);
1240 printf(" n | %f | %f\n",p->n[0],p->n[1]);
1241 printf(" c | %f | %f\n",p->c[0],p->c[1]);
1242 printf(" d | %f | %f\n",p->d[0],p->d[1]);
1243 printf(" h | %f | %f\n",p->h[0],p->h[1]);
1244 printf(" chi | %f \n",p->chi);
1249 /* tersoff 1 body part */
1250 int tersoff_mult_1bp(t_moldyn *moldyn,t_atom *ai) {
1253 t_tersoff_mult_params *params;
1254 t_tersoff_exchange *exchange;
1257 params=moldyn->pot1b_params;
1258 exchange=&(params->exchange);
1261 * simple: point constant parameters only depending on atom i to
1262 * their right values
1265 exchange->beta_i=&(params->beta[brand]);
1266 exchange->n_i=&(params->n[brand]);
1267 exchange->c_i=&(params->c[brand]);
1268 exchange->d_i=&(params->d[brand]);
1269 exchange->h_i=&(params->h[brand]);
1271 exchange->betaini=pow(*(exchange->beta_i),*(exchange->n_i));
1272 exchange->ci2=params->c[brand]*params->c[brand];
1273 exchange->di2=params->d[brand]*params->d[brand];
1274 exchange->ci2di2=exchange->ci2/exchange->di2;
1279 /* tersoff 2 body part */
1280 int tersoff_mult_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
1282 t_tersoff_mult_params *params;
1283 t_tersoff_exchange *exchange;
1284 t_3dvec dist_ij,force;
1286 double A,B,R,S,lambda,mu;
1293 params=moldyn->pot2b_params;
1295 exchange=&(params->exchange);
1297 /* clear 3bp and 2bp post run */
1299 exchange->run2bp_post=0;
1301 /* reset S > r > R mark */
1302 exchange->d_ij_between_rs=0;
1305 * calc of 2bp contribution of V_ij and dV_ij/ji
1307 * for Vij and dV_ij we need:
1311 * for dV_ji we need:
1312 * - f_c_ji = f_c_ij, df_c_ji = df_c_ij
1313 * - f_r_ji = f_r_ij; df_r_ji = df_r_ij
1318 v3_sub(&dist_ij,&(aj->r),&(ai->r));
1319 if(bc) check_per_bound(moldyn,&dist_ij);
1320 d_ij=v3_norm(&dist_ij);
1322 /* save for use in 3bp */
1323 exchange->d_ij=d_ij;
1324 exchange->dist_ij=dist_ij;
1327 if(brand==ai->brand) {
1332 lambda=params->lambda[brand];
1333 mu=params->mu[brand];
1341 lambda=params->lambda_m;
1343 params->exchange.chi=params->chi;
1346 /* if d_ij > S => no force & potential energy contribution */
1350 /* more constants */
1351 exchange->beta_j=&(params->beta[brand]);
1352 exchange->n_j=&(params->n[brand]);
1353 exchange->c_j=&(params->c[brand]);
1354 exchange->d_j=&(params->d[brand]);
1355 exchange->h_j=&(params->h[brand]);
1356 if(brand==ai->brand) {
1357 exchange->betajnj=exchange->betaini;
1358 exchange->cj2=exchange->ci2;
1359 exchange->dj2=exchange->di2;
1360 exchange->cj2dj2=exchange->ci2di2;
1363 exchange->betajnj=pow(*(exchange->beta_j),*(exchange->n_j));
1364 exchange->cj2=params->c[brand]*params->c[brand];
1365 exchange->dj2=params->d[brand]*params->d[brand];
1366 exchange->cj2dj2=exchange->cj2/exchange->dj2;
1369 /* f_r_ij = f_r_ji, df_r_ij = df_r_ji */
1370 f_r=A*exp(-lambda*d_ij);
1371 df_r=lambda*f_r/d_ij;
1373 /* f_a, df_a calc (again, same for ij and ji) | save for later use! */
1374 exchange->f_a=-B*exp(-mu*d_ij);
1375 exchange->df_a=mu*exchange->f_a/d_ij;
1377 /* f_c, df_c calc (again, same for ij and ji) */
1379 /* f_c = 1, df_c = 0 */
1382 /* two body contribution (ij, ji) */
1383 v3_scale(&force,&dist_ij,-df_r);
1387 arg=M_PI*(d_ij-R)/s_r;
1388 f_c=0.5+0.5*cos(arg);
1389 //df_c=-0.5*sin(arg)*(M_PI/(s_r*d_ij)); /* MARK! */
1390 df_c=0.5*sin(arg)*(M_PI/(s_r*d_ij));
1391 /* two body contribution (ij, ji) */
1392 v3_scale(&force,&dist_ij,-df_c*f_r-df_r*f_c);
1393 /* tell 3bp that S > r > R */
1394 exchange->d_ij_between_rs=1;
1397 /* add forces of 2bp (ij, ji) contribution
1398 * dVij = dVji and we sum up both: no 1/2) */
1399 v3_add(&(ai->f),&(ai->f),&force);
1401 /* energy 2bp contribution (ij, ji) is 0.5 f_r f_c ... */
1402 moldyn->energy+=(0.5*f_r*f_c);
1404 /* save for use in 3bp */
1406 exchange->df_c=df_c;
1408 /* enable the run of 3bp function and 2bp post processing */
1410 exchange->run2bp_post=1;
1412 /* reset 3bp sums */
1413 exchange->zeta_ij=0.0;
1414 exchange->zeta_ji=0.0;
1415 v3_zero(&(exchange->dzeta_ij));
1416 v3_zero(&(exchange->dzeta_ji));
1421 /* tersoff 2 body post part */
1423 int tersoff_mult_post_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
1426 * here we have to allow for the 3bp sums
1429 * - zeta_ij, dzeta_ij
1430 * - zeta_ji, dzeta_ji
1432 * to compute the 3bp contribution to:
1438 t_tersoff_mult_params *params;
1439 t_tersoff_exchange *exchange;
1444 double f_c,df_c,f_a,df_a;
1445 double chi,ni,betaini,nj,betajnj;
1448 params=moldyn->pot2b_params;
1449 exchange=&(params->exchange);
1451 /* we do not run if f_c_ij was detected to be 0! */
1452 if(!(exchange->run2bp_post))
1456 df_c=exchange->df_c;
1458 df_a=exchange->df_a;
1459 betaini=exchange->betaini;
1460 betajnj=exchange->betajnj;
1461 ni=*(exchange->n_i);
1462 nj=*(exchange->n_j);
1464 dist_ij=&(exchange->dist_ij);
1467 zeta=exchange->zeta_ij;
1469 moldyn->debug++; /* just for debugging ... */
1472 v3_scale(&force,dist_ij,df_a*b*f_c);
1475 tmp=betaini*pow(zeta,ni-1.0); /* beta^n * zeta^n-1 */
1476 b=(1+zeta*tmp); /* 1 + beta^n zeta^n */
1477 db=chi*pow(b,-1.0/(2*ni)-1); /* x(...)^(-1/2n - 1) */
1479 db*=-0.5*tmp; /* db_ij */
1480 v3_scale(&force,&(exchange->dzeta_ij),f_a*db);
1481 v3_scale(&temp,dist_ij,df_a*b);
1482 v3_add(&force,&force,&temp);
1483 v3_scale(&force,&force,f_c);
1485 v3_scale(&temp,dist_ij,df_c*b*f_a);
1486 v3_add(&force,&force,&temp);
1487 v3_scale(&force,&force,-0.5);
1490 v3_add(&(ai->f),&(ai->f),&force);
1492 /* add energy of 3bp sum */
1493 moldyn->energy+=(0.5*f_c*b*f_a);
1496 zeta=exchange->zeta_ji;
1500 v3_scale(&force,dist_ij,df_a*b*f_c);
1503 tmp=betajnj*pow(zeta,nj-1.0); /* beta^n * zeta^n-1 */
1504 b=(1+zeta*tmp); /* 1 + beta^n zeta^n */
1505 db=chi*pow(b,-1.0/(2*nj)-1); /* x(...)^(-1/2n - 1) */
1507 db*=-0.5*tmp; /* db_ij */
1508 v3_scale(&force,&(exchange->dzeta_ji),f_a*db);
1509 v3_scale(&temp,dist_ij,df_a*b);
1510 v3_add(&force,&force,&temp);
1511 v3_scale(&force,&force,f_c);
1513 v3_scale(&temp,dist_ij,df_c*b*f_a);
1514 v3_add(&force,&force,&temp);
1515 v3_scale(&force,&force,-0.5);
1518 v3_add(&(ai->f),&(ai->f),&force);
1523 /* tersoff 3 body part */
1525 int tersoff_mult_3bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,t_atom *ak,u8 bc) {
1527 t_tersoff_mult_params *params;
1528 t_tersoff_exchange *exchange;
1529 t_3dvec dist_ij,dist_ik,dist_jk;
1530 t_3dvec temp1,temp2;
1534 double d_ij,d_ik,d_jk;
1537 double f_c_ik,df_c_ik,arg;
1541 double cos_theta,d_costheta1,d_costheta2;
1542 double h_cos,d2_h_cos2;
1543 double frac,g,zeta,chi;
1547 params=moldyn->pot3b_params;
1548 exchange=&(params->exchange);
1550 if(!(exchange->run3bp))
1554 * calc of 3bp contribution of V_ij and dV_ij/ji/jk &
1555 * 2bp contribution of dV_jk
1557 * for Vij and dV_ij we still need:
1558 * - b_ij, db_ij (zeta_ij)
1559 * - f_c_ik, df_c_ik, constants_i, cos_theta_ijk, d_costheta_ijk
1561 * for dV_ji we still need:
1562 * - b_ji, db_ji (zeta_ji)
1563 * - f_c_jk, d_c_jk, constants_j, cos_theta_jik, d_costheta_jik
1565 * for dV_jk we need:
1569 * - f_c_ji, df_c_ji, constants_j, cos_theta_jki, d_costheta_jki
1577 /* dist_ij, d_ij - this is < S_ij ! */
1578 dist_ij=exchange->dist_ij;
1579 d_ij=exchange->d_ij;
1581 /* f_c_ij, df_c_ij (same for ji) */
1583 df_c=exchange->df_c;
1586 * calculate unknown values now ...
1589 /* V_ij and dV_ij stuff (in b_ij there is f_c_ik) */
1592 v3_sub(&dist_ik,&(ak->r),&(ai->r));
1593 if(bc) check_per_bound(moldyn,&dist_ik);
1594 d_ik=v3_norm(&dist_ik);
1598 if(brand==ak->brand) {
1607 /* zeta_ij/dzeta_ij contribution only for d_ik < S */
1610 /* get constants_i from exchange data */
1617 c2d2=exchange->ci2di2;
1619 /* cosine of theta_ijk by scalaproduct */
1620 rr=v3_scalar_product(&dist_ij,&dist_ik);
1626 d_costheta1=cos_theta/(d_ij*d_ij)-tmp;
1627 d_costheta2=cos_theta/(d_ik*d_ik)-tmp;
1629 /* some usefull values */
1630 h_cos=(h-cos_theta);
1631 d2_h_cos2=d2+(h_cos*h_cos);
1632 frac=c2/(d2_h_cos2);
1637 /* d_costheta_ij and dg(cos_theta) - needed in any case! */
1638 v3_scale(&temp1,&dist_ij,d_costheta1);
1639 v3_scale(&temp2,&dist_ik,d_costheta2);
1640 v3_add(&temp1,&temp1,&temp2);
1641 v3_scale(&temp1,&temp1,-2.0*frac*h_cos/d2_h_cos2); /* dg */
1643 /* f_c_ik & df_c_ik + {d,}zeta contribution */
1644 dzeta=&(exchange->dzeta_ij);
1648 // => df_c_ik=0.0; of course we do not set this!
1651 exchange->zeta_ij+=g;
1654 v3_add(dzeta,dzeta,&temp1);
1659 arg=M_PI*(d_ik-R)/s_r;
1660 f_c_ik=0.5+0.5*cos(arg);
1661 //df_c_ik=-0.5*sin(arg)*(M_PI/(s_r*d_ik)); /* MARK */
1662 df_c_ik=0.5*sin(arg)*(M_PI/(s_r*d_ik));
1665 exchange->zeta_ij+=f_c_ik*g;
1668 v3_scale(&temp1,&temp1,f_c_ik);
1669 v3_scale(&temp2,&dist_ik,g*df_c_ik);
1670 v3_add(&temp1,&temp1,&temp2);
1671 v3_add(dzeta,dzeta,&temp1);
1675 /* dV_ji stuff (in b_ji there is f_c_jk) + dV_jk stuff! */
1678 v3_sub(&dist_jk,&(ak->r),&(aj->r));
1679 if(bc) check_per_bound(moldyn,&dist_jk);
1680 d_jk=v3_norm(&dist_jk);
1684 if(brand==ak->brand) {
1688 mu=params->mu[brand];
1699 /* zeta_ji/dzeta_ji contribution only for d_jk < S_jk */
1702 /* constants_j from exchange data */
1709 c2d2=exchange->cj2dj2;
1711 /* cosine of theta_jik by scalaproduct */
1712 rr=-v3_scalar_product(&dist_ij,&dist_jk); /* -1, as ij -> ji */
1718 d_costheta2=cos_theta/(d_ij*d_ij);
1720 /* some usefull values */
1721 h_cos=(h-cos_theta);
1722 d2_h_cos2=d2+(h_cos*h_cos);
1723 frac=c2/(d2_h_cos2);
1728 /* d_costheta_ij and dg(cos_theta) - needed in any case! */
1729 v3_scale(&temp1,&dist_jk,d_costheta1);
1730 v3_scale(&temp2,&dist_ij,-d_costheta2); /* ji -> ij => -1 */
1731 v3_add(&temp1,&temp1,&temp2);
1732 v3_scale(&temp1,&temp1,-2.0*frac*h_cos/d2_h_cos2); /* dg */
1734 /* store dg in temp2 and use it for dVjk later */
1735 v3_copy(&temp2,&temp1);
1737 /* f_c_jk + {d,}zeta contribution (df_c_jk = 0) */
1738 dzeta=&(exchange->dzeta_ji);
1744 exchange->zeta_ji+=g;
1747 v3_add(dzeta,dzeta,&temp1);
1752 arg=M_PI*(d_jk-R)/s_r;
1753 f_c_jk=0.5+0.5*cos(arg);
1756 exchange->zeta_ji+=f_c_jk*g;
1759 v3_scale(&temp1,&temp1,f_c_jk);
1760 v3_add(dzeta,dzeta,&temp1);
1763 /* dV_jk stuff | add force contribution on atom i immediately */
1764 if(exchange->d_ij_between_rs) {
1766 v3_scale(&temp1,&temp2,f_c);
1767 v3_scale(&temp2,&dist_ij,df_c*g);
1768 v3_add(&temp2,&temp2,&temp1); /* -> dzeta_jk in temp2 */
1772 // dzeta_jk is simply dg, which is stored in temp2
1774 /* betajnj * zeta_jk ^ nj-1 */
1775 tmp=exchange->betajnj*pow(zeta,(n-1.0));
1776 tmp=-chi/2.0*pow((1+tmp*zeta),(-1.0/(2.0*n)-1))*tmp;
1777 v3_scale(&temp2,&temp2,tmp*B*exp(-mu*d_jk)*f_c_jk*0.5);
1778 v3_add(&(ai->f),&(ai->f),&temp2); /* -1 skipped in f_a calc ^ */
1779 /* scaled with 0.5 ^ */
1788 * debugging / critical check functions
1791 int moldyn_bc_check(t_moldyn *moldyn) {
1804 for(i=0;i<moldyn->count;i++) {
1805 if(atom[i].r.x>=dim->x/2||-atom[i].r.x>dim->x/2) {
1806 printf("FATAL: atom %d: x: %.20f (%.20f)\n",
1807 i,atom[i].r.x,dim->x/2);
1808 printf("diagnostic:\n");
1809 printf("-----------\natom.r.x:\n");
1811 memcpy(&byte,(u8 *)(&(atom[i].r.x))+j,1);
1814 ((byte)&(1<<k))?1:0,
1817 printf("---------------\nx=dim.x/2:\n");
1819 memcpy(&byte,(u8 *)(&x)+j,1);
1822 ((byte)&(1<<k))?1:0,
1825 if(atom[i].r.x==x) printf("the same!\n");
1826 else printf("different!\n");
1828 if(atom[i].r.y>=dim->y/2||-atom[i].r.y>dim->y/2)
1829 printf("FATAL: atom %d: y: %.20f (%.20f)\n",
1830 i,atom[i].r.y,dim->y/2);
1831 if(atom[i].r.z>=dim->z/2||-atom[i].r.z>dim->z/2)
1832 printf("FATAL: atom %d: z: %.20f (%.20f)\n",
1833 i,atom[i].r.z,dim->z/2);