- return 0;
-}
-
-/* tersoff 1 body part */
-int tersoff_mult_1bp(t_moldyn *moldyn,t_atom *ai) {
-
- int num;
- t_tersoff_mult_params *params;
- t_tersoff_exchange *exchange;
-
- num=ai->bnum;
- params=moldyn->pot1b_params;
- exchange=&(params->exchange);
-
- /*
- * simple: point constant parameters only depending on atom i to
- * their right values
- */
-
- exchange->beta=&(params->beta[num]);
- exchange->n=&(params->n[num]);
- exchange->c=&(params->c[num]);
- exchange->d=&(params->d[num]);
- exchange->h=&(params->h[num]);
-
- exchange->betan=pow(*(exchange->beta),*(exchange->n));
- exchange->n_betan=*(exchange->n)*exchange->betan;
- exchange->c2=params->c[num]*params->c[num];
- exchange->d2=params->d[num]*params->d[num];
- exchange->c2d2=exchange->c2/exchange->d2;
-
- return 0;
-}
-
-/* tersoff 2 body part */
-int tersoff_mult_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
-
- t_tersoff_mult_params *params;
- t_tersoff_exchange *exchange;
- t_3dvec dist_ij,force;
- double d_ij;
- double A,B,R,S,lambda,mu;
- double f_r,df_r;
- double f_c,df_c;
- int num;
- double s_r;
- double arg;
- double scale;
-
- params=moldyn->pot2b_params;
- num=ai->bnum;
- exchange=&(params->exchange);
-
- exchange->run3bp=0;
-
- /*
- * we need: f_c, df_c, f_r, df_r
- *
- * therefore we need: R, S, A, lambda
- */
-
- v3_sub(&dist_ij,&(ai->r),&(aj->r));
-
- if(bc) check_per_bound(moldyn,&dist_ij);
-
- d_ij=v3_norm(&dist_ij);
-
- /* save for use in 3bp */
- exchange->d_ij=d_ij;
- exchange->dist_ij=dist_ij;
- exchange->d_ij2=d_ij*d_ij;
-
- /* constants */
- if(num==aj->bnum) {
- S=params->S[num];
- R=params->R[num];
- A=params->A[num];
- B=params->B[num];
- lambda=params->lambda[num];
- mu=params->mu[num];
- params->exchange.chi=1.0;
- }
- else {
- S=params->Smixed;
- R=params->Rmixed;
- A=params->Amixed;
- B=params->Bmixed;
- lambda=params->lambda_m;
- mu=params->mu_m;
- params->exchange.chi=params->chi;
- }
-
- if(d_ij>S)
- return 0;
-
- f_r=A*exp(-lambda*d_ij);
- df_r=-lambda*f_r/d_ij;
-
- /* f_a, df_a calc + save for 3bp use */
- exchange->f_a=-B*exp(-mu*d_ij);
- exchange->df_a=-mu*exchange->f_a/d_ij;
-
- if(d_ij<R) {
- /* f_c = 1, df_c = 0 */
- f_c=1.0;
- df_c=0.0;
- v3_scale(&force,&dist_ij,df_r);
- }
- else {
- s_r=S-R;
- arg=M_PI*(d_ij-R)/s_r;
- f_c=0.5+0.5*cos(arg);
- df_c=-0.5*sin(arg)*(M_PI/(s_r*d_ij));
- scale=df_c*f_r+df_r*f_c;
- v3_scale(&force,&dist_ij,scale);
- }
-
- /* add forces */
- v3_add(&(ai->f),&(ai->f),&force);
- /* energy is 0.5 f_r f_c ... */
- moldyn->energy+=(0.5*f_r*f_c);
-
- /* save for use in 3bp */
- exchange->f_c=f_c;
- exchange->df_c=df_c;
-
- /* enable the run of 3bp function */
- exchange->run3bp=1;
-
- /* reset 3bp sums */
- exchange->sum1_3bp=0.0;
- exchange->sum2_3bp=0.0;
- v3_zero(&(exchange->db_ij));
-
- 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 */
-
- t_tersoff_mult_params *params;
- t_tersoff_exchange *exchange;
-
- t_3dvec force,temp,*db_ij,*dist_ij;
- double db_ij_scale1,db_ij_scale2;
- double b_ij;
- double f_c,df_c,f_a,df_a;
- double chi,betan;
- double help;
- double n;
-
- params=moldyn->pot2b_params;
- exchange=&(params->exchange);
-
- db_ij=&(exchange->db_ij);
- f_c=exchange->f_c;
- df_c=exchange->df_c;
- f_a=exchange->f_a;
- df_a=exchange->df_a;
- betan=exchange->betan;
- n=*(exchange->n);
- dist_ij=&(exchange->dist_ij);
-
- db_ij_scale1=(1+betan*exchange->sum1_3bp);
- db_ij_scale2=(exchange->n_betan*exchange->sum2_3bp);
- help=pow(db_ij_scale1,-1.0/(2*n)-1);
- b_ij=chi*db_ij_scale1*help;
- db_ij_scale1=-chi/(2*n)*help;
-
- v3_scale(db_ij,db_ij,(db_ij_scale1*db_ij_scale2));
- v3_scale(db_ij,db_ij,f_a);
-
- v3_scale(&temp,dist_ij,b_ij*df_a);
-
- v3_add(&force,&temp,db_ij);
- v3_scale(&force,&force,f_c);
-
- v3_scale(&temp,dist_ij,f_a*b_ij*df_c);
-
- /* add energy of 3bp sum */
- moldyn->energy+=(0.5*f_c*b_ij*f_a);
- /* add force of 3bp calculation */
- v3_add(&(ai->f),&temp,&force);
-
- return 0;
-}
-
-/* tersoff 3 body part */
-
-int tersoff_mult_3bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,t_atom *ak,u8 bc) {
-
- t_tersoff_mult_params *params;
- t_tersoff_exchange *exchange;
- t_3dvec dist_ij,dist_ik,dist_jk;
- t_3dvec temp,force;
- double R,S,s_r;
- double d_ij,d_ij2,d_ik,d_jk;
- double f_c,df_c,f_a,df_a;
- double f_c_ik,df_c_ik,arg;
- double n,c,d,h;
- double c2,d2,c2d2;
- double numer,denom;
- double theta,cos_theta,sin_theta;
- double d_theta,d_theta1,d_theta2;
- double h_cos,d2_h_cos2;
- double frac,bracket,bracket_n_1,bracket_n;
- double g;
- int num;
-
- params=moldyn->pot3b_params;
- num=ai->bnum;
- exchange=&(params->exchange);
-
- if(!(exchange->run3bp))
- return 0;
-
- /*
- * we need: f_c, d_fc, b_ij, db_ij, f_a, df_a
- *
- * we got f_c, df_c, f_a, df_a from 2bp calculation
- */
-
- d_ij=exchange->d_ij;
- d_ij2=exchange->d_ij2;
- dist_ij=exchange->dist_ij;
-
- f_a=params->exchange.f_a;
- df_a=params->exchange.df_a;
-
- f_c=exchange->f_c;
- df_c=exchange->df_c;
-
- /* d_ij is <= S, as we didn't return so far! */
-
- /*
- * calc of b_ij (scalar) and db_ij (vector)
- *
- * - for b_ij: chi, beta, f_c_ik, w(=1), c, d, h, n, cos_theta
- *
- * - for db_ij: d_theta, sin_theta, cos_theta, f_c_ik, df_c_ik,
- * w_ik,
- *
- */
-
- v3_sub(&dist_ik,&(ai->r),&(ak->r));
- if(bc) check_per_bound(moldyn,&dist_ik);
- d_ik=v3_norm(&dist_ik);