+int force_lennard_jones(t_moldyn *moldyn) {
+
+ t_lj_params *params;
+ int i,j,count;
+ t_atom *atom;
+ t_3dvec distance;
+ t_3dvec force;
+ double d,h1,h2;
+
+ atom=moldyn->atom;
+ count=moldyn->count;
+ params=moldyn->pot_params;
+
+ for(i=0;i<count;i++) {
+ for(j=0;j<i;j++) {
+ v3_sub(&distance,&(atom[j].r),&(atom[i].r));
+ v3_per_bound(&distance,&(moldyn->dim));
+ d=v3_absolute_square(&distance);
+ if(d<=moldyn->cutoff_square) {
+ h1=1.0/d; /* 1/r^2 */
+ d=h1*h1; /* 1/r^4 */
+ h2=d*d; /* 1/r^8 */
+ h1*=d; /* 1/r^6 */
+ h1*=h2; /* 1/r^14 */
+ }
+ }
+ }
+
+ return 0;
+}