Files
rdkit/Code/ForceField/MMFF/BondStretch.cpp
ptosco ba4a48ce05 - fixed a bug in Code/ForceField/MMFF/testMMFFForceField.cpp
- fixed a bug in Code/GraphMol/ForceFieldHelpers/MMFF/AtomTyper.cpp
  which caused misassignment of atom types in CYGUAN01 upon shuffling
  the order of atoms in the validation SDF files
- added checks for acos and asin function parameters to be within
  a (-1, 1) range
2014-06-01 16:23:03 +01:00

105 lines
3.0 KiB
C++

// $Id$
//
// Copyright (C) 2013 Paolo Tosco
//
// Copyright (C) 2004-2006 Rational Discovery LLC
//
// @@ All Rights Reserved @@
// This file is part of the RDKit.
// The contents are covered by the terms of the BSD license
// which is included in the file license.txt, found at the root
// of the RDKit source tree.
//
#include "BondStretch.h"
#include "Params.h"
#include <cmath>
#include <ForceField/ForceField.h>
#include <RDGeneral/Invariant.h>
#include <RDGeneral/utils.h>
namespace ForceFields {
namespace MMFF {
namespace Utils {
double calcBondRestLength(const MMFFBond *mmffBondParams)
{
PRECONDITION(mmffBondParams, "bond parameters not found");
return mmffBondParams->r0;
}
double calcBondForceConstant(const MMFFBond *mmffBondParams)
{
PRECONDITION(mmffBondParams, "bond parameters not found");
return mmffBondParams->kb;
}
double calcBondStretchEnergy(const double r0, const double kb, const double distance)
{
double distTerm = distance - r0;
double distTerm2 = distTerm * distTerm;
double const c1 = 143.9325;
double const cs = -2.0;
double const c3 = 7.0 / 12.0;
return (0.5 * c1 * kb * distTerm2
* (1.0 + cs * distTerm + c3 * cs * cs * distTerm2));
}
} // end of namespace Utils
BondStretchContrib::BondStretchContrib(ForceField *owner,
const unsigned int idx1, const unsigned int idx2,
const MMFFBond *mmffBondParams)
{
PRECONDITION(owner,"bad owner");
RANGE_CHECK(0, idx1, owner->positions().size() - 1);
RANGE_CHECK(0, idx2, owner->positions().size() - 1);
dp_forceField = owner;
d_at1Idx = idx1;
d_at2Idx = idx2;
d_r0 = mmffBondParams->r0;
d_kb = mmffBondParams->kb;
}
double BondStretchContrib::getEnergy(double *pos) const
{
PRECONDITION(dp_forceField,"no owner");
PRECONDITION(pos,"bad vector");
return Utils::calcBondStretchEnergy(d_r0, d_kb,
dp_forceField->distance(d_at1Idx, d_at2Idx, pos));
}
void BondStretchContrib::getGrad(double *pos, double *grad) const
{
PRECONDITION(dp_forceField,"no owner");
PRECONDITION(pos, "bad vector");
PRECONDITION(grad, "bad vector");
double dist = dp_forceField->distance
(d_at1Idx, d_at2Idx, pos);
double *at1Coords = &(pos[3 * d_at1Idx]);
double *at2Coords = &(pos[3 * d_at2Idx]);
double *g1 = &(grad[3 * d_at1Idx]);
double *g2 = &(grad[3 * d_at2Idx]);
double const cs = -2.0;
double const c1 = 143.9325;
double const c3 = 7.0 / 12.0;
double distTerm = dist - d_r0;
double dE_dr = c1 * d_kb * distTerm
* (1.0 + 1.5 * cs * distTerm + 2.0 * c3 * cs * cs * distTerm * distTerm);
double dGrad;
for (unsigned int i = 0; i < 3; ++i) {
dGrad = ((dist > 0.0)
? (dE_dr * (at1Coords[i] - at2Coords[i]) / dist) : d_kb * 0.01);
g1[i] += dGrad;
g2[i] -= dGrad;
}
}
}
}