From 7fcb896467bdf236f60c4c3784a9d51214737fcb Mon Sep 17 00:00:00 2001
From: hackbard <hackbard>
Date: Thu, 3 May 2007 09:43:08 +0000
Subject: [PATCH] fixed sign

---
 potentials/tersoff.c      | 10 +++++-----
 potentials/tersoff_orig.c |  2 +-
 sic.c                     | 12 ++++++++++--
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/potentials/tersoff.c b/potentials/tersoff.c
index 531d292..b6533e1 100644
--- 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 90121f2..69b67ac 100644
--- 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 a78f3a0..714710b 100644
--- 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,
-- 
2.20.1