if(bc) check_per_bound(moldyn,&distance);
d=v3_norm(&distance);
if(d<=moldyn->cutoff) {
/* energy is 1/2 (d-d0)^2, but we will add this twice ... */
moldyn->energy+=(0.25*sc*(d-equi_dist)*(d-equi_dist));
if(bc) check_per_bound(moldyn,&distance);
d=v3_norm(&distance);
if(d<=moldyn->cutoff) {
/* energy is 1/2 (d-d0)^2, but we will add this twice ... */
moldyn->energy+=(0.25*sc*(d-equi_dist)*(d-equi_dist));