Pair Coul Wolf

Why two separate calls to ev_Tally?

This has been bothering me for some time, and I think may be a major source of difficulty in trying to integrate the use of wolf charges into vmm. As far as I understand wolf charge it should be two summations one over just i and the other over i-j, the first being a charge background term and the second the more traditional pairwise interaction. Its really the first call to ev_Tally that bothers me. The second makes more sense. Why can’t you just add the energy from the first part into the second?

matthew

Why two separate calls to ev_Tally?

This has been bothering me for some time, and I think may be a major
source of difficulty in trying to integrate the use of wolf charges into
vmm. As far as I understand wolf charge it should be two summations one
over just i and the other over i-j, the first being a charge background
term and the second the more traditional pairwise interaction. Its really
the first call to ev_Tally that bothers me. The second makes more sense.
Why can't you just add the energy from the first part into the second?

​because the first call is only adding terms to atom i and thus not a
pairwise term, while the second​ attributes contributions to both atoms in
a pair i j with i != j.
so it actually matches perfectly with the two sums you are talking about.

axel.