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Detect and remove duplicate dihedrals with the same periodicity #530

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14 changes: 13 additions & 1 deletion src/FFSetup.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -380,14 +380,26 @@ void Dihedral::Read(Reader &param, std::string const &firstVar) {
if (index == 0) {
// set phase shift for n=0 to 90 degree
// We will have C0 = Kchi (1 + cos(0 * phi + 90)) = Kchi
//this avoids double counting the C0 (constant offset) term, which is used force fields like TraPPE
// this avoids double counting the C0 (constant offset) term, which is used
// in force fields like TraPPE
def = 90.00;
}
Add(merged, coeff, index, def);
last = merged;
}
void Dihedral::Add(std::string const &merged, const double coeff,
const uint index, const double def) {
// Check for (and skip) duplicate periodicities for the same dihedral
bool duplicate = false;
for (auto it = n[merged].begin(); it != n[merged].end(); ++it) {
duplicate |= *it == index;
}

if (duplicate) {
std::cout << "Warning: Skipping duplicate periodicity of " << index
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This patch works as intended per my testing.

I looked at what NAMD does. It appears they take the last one input. We may want to be consistent with them for py-mcmd.

My last comment, is more of a question, and this would go for non-bonded and all bonded parameters.

Do we want to more than NAMD and check if the parameters are the same or different (this would be more than NAMD):

  • if the same, skip it
  • if different, throw an error or overwrite with the last one.

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I tested is and it Looks like it is working as intended.

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I updated the patch so that it throws an error if the parameters differ by more than 0.001. I have to imagine that would be a mistake. Since it only proceeds if they match, then which one we save doesn't matter.

So, we do the same thing as NAMD if the parameters match except we also issue a warning, and we terminate with an error if the parameters differ.

<< " for dihedral " << merged << "!\n";
return;
}
++countTerms;
Kchi[merged].push_back(EnConvIfCHARMM(coeff));
n[merged].push_back(index);
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