fixed sign

diff --git a/potentials/tersoff.c b/potentials/tersoff.c
index 531d292131121ad5acb7b1ce2a4a0c551199b34a..b6533e19bf90c3709b5915198c6a2964be2efc41 100644 (file)
--- a/potentials/tersoff.c
+++ b/potentials/tersoff.c
@@ -153,7 +153,7 @@ int tersoff_mult_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
 
        /* add forces */
        v3_add(&(ai->f),&(ai->f),&force);
-       v3_sub(&(aj->f),&(aj->f),&force);
+       v3_sub(&(aj->f),&(aj->f),&force); // reason: dri rij = - drj rij
 
 #ifdef DEBUG
        if((ai==&(moldyn->atom[0]))|(aj==&(moldyn->atom[0]))) {
@@ -388,7 +388,7 @@ int tersoff_mult_3bp_j2(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
                ni=*(exchange->n_i);
                tmp=exchange->betaini*pow(exchange->zeta_ij,ni-1.0);
                b=(1.0+exchange->zeta_ij*tmp);
-               db=chi*pow(b,-1.0/(2*ni)-1.0);
+               db=chi*pow(b,-1.0/(2.0*ni)-1.0);
                b=db*b;
                db*=-0.5*tmp;
        }
@@ -397,7 +397,7 @@ int tersoff_mult_3bp_j2(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
        v3_scale(&force,&(exchange->dist_ij),df_a*f_c+f_a*df_c);
        v3_scale(&force,&force,-0.5*b);
        v3_add(&(ai->f),&(ai->f),&force);
-       v3_sub(&(aj->f),&(aj->f),&force);
+       v3_sub(&(aj->f),&(aj->f),&force); // dri rij = - drj rij
 
 #ifdef DEBUG
        if((ai==&(moldyn->atom[0]))|(aj==&(moldyn->atom[0]))) {
@@ -522,7 +522,7 @@ int tersoff_mult_3bp_k2(t_moldyn *moldyn,
        /* virial */
        //virial_calc(ai,&force,&dist_ij);
 
-       /* derivatice wrt j */
+       /* derivative wrt j */
        v3_scale(&force,&dcosdrj,fcdg*pre_dzeta);
 
        /* force contribution */
@@ -540,7 +540,7 @@ int tersoff_mult_3bp_k2(t_moldyn *moldyn,
        //virial_calc(aj,&force,&dist_ij);
 
        /* derivative wrt k */
-       v3_scale(&force,&dist_ik,dfcg);
+       v3_scale(&force,&dist_ik,-1.0*dfcg); // dri rij = - drj rij
        v3_scale(&tmp,&dcosdrk,fcdg);
        v3_add(&force,&force,&tmp);
        v3_scale(&force,&force,pre_dzeta);

diff --git a/potentials/tersoff_orig.c b/potentials/tersoff_orig.c
index 90121f26bb1cda4855e75abb27a418c66089a177..69b67ace63e630a7a0b6fe623aae269e57094f17 100644 (file)
--- a/potentials/tersoff_orig.c
+++ b/potentials/tersoff_orig.c
@@ -310,7 +310,7 @@ int tersoff_mult_post_2bp(t_moldyn *moldyn,t_atom *ai,t_atom *aj,u8 bc) {
        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) */
+               db=chi*pow(b,-1.0/(2.0*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);

diff --git a/sic.c b/sic.c
index a78f3a0a9396318d91ddf5d3662eaeb2215e7ea9..714710b579257452f2600517ad897c7e614d4d12 100644 (file)
--- a/sic.c
+++ b/sic.c
@@ -194,9 +194,17 @@ int main(int argc,char **argv) {
        //           ATOM_ATTR_1BP|ATOM_ATTR_2BP|ATOM_ATTR_3BP|ATOM_ATTR_HB,
        //           ATOM_ATTR_2BP|ATOM_ATTR_HB,
        //           &r,&v);
+       //r.z=0.27*sqrt(3.0)*LC_SI/2.0; v.z=0;
+       //r.x=(TM_S_SI+TM_R_SI)/4.0;    v.x=0;
+       //r.y=0;                v.y=0;
+       //r.x=0;                v.x=0;
+       //add_atom(&md,SI,M_SI,0,
+       //           ATOM_ATTR_1BP|ATOM_ATTR_2BP|ATOM_ATTR_3BP|ATOM_ATTR_HB,
+       //           ATOM_ATTR_2BP|ATOM_ATTR_HB,
+       //           &r,&v);
+       //r.z=-r.z;     v.z=-v.z;
+       //r.y=0;                v.y=0;
        //r.x=0;                v.x=0;
-       //r.y=0;        v.y=0;
-       //r.z=sin(M_PI*60.0/180.0)*(TM_S_SI+TM_R_SI)/4.0;       v.z=0;
        //add_atom(&md,SI,M_SI,0,
        //           ATOM_ATTR_1BP|ATOM_ATTR_2BP|ATOM_ATTR_3BP|ATOM_ATTR_HB,
        //           ATOM_ATTR_2BP|ATOM_ATTR_HB,