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/*
* sketcherMinimizerStretchInteraction.h
*
* Created by Nicola Zonta on 13/04/2010.
* Copyright Schrodinger, LLC. All rights reserved.
*
*/
#ifndef sketcherMINIMIZERSTRETCHMINIMIZERINTERACTION
#define sketcherMINIMIZERSTRETCHMINIMIZERINTERACTION
#include "sketcherMinimizerInteraction.h"
/* force field bond stretches */
class sketcherMinimizerStretchInteraction : public sketcherMinimizerInteraction
{
public:
sketcherMinimizerStretchInteraction(sketcherMinimizerAtom* at1,
sketcherMinimizerAtom* at2)
: sketcherMinimizerInteraction(at1, at2)
{
}
~sketcherMinimizerStretchInteraction() override = default;
/* calculate forces and apply them */
void score(float& totalE, bool = false) override
{
energy(totalE);
sketcherMinimizerPointF l = atom1->coordinates - atom2->coordinates;
float m = l.length();
float dr = 0;
if (m < restV - tolerance) dr = restV - tolerance - m;
else if (m > restV + tolerance) dr = restV + tolerance - m;
else return;
float shortBondThreshold = restV * 0.4f;
float penaltyForVeryShortBonds = (shortBondThreshold - m);
if (penaltyForVeryShortBonds < 0) {
penaltyForVeryShortBonds = 0;
}
if (m > SKETCHER_EPSILON) {
l /= m;
}
l *= (k * dr + penaltyForVeryShortBonds * 10);
atom1->force += l;
atom2->force -= l;
}
float tolerance = 0;
};
#endif // sketcherMINIMIZERSTRETCHINTERACTION
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