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Open Source Chemistry Library
/*
* Copyright 2013-2020 Thomas Sander, openmolecules.org
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its contributors
* may be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @author Thomas Sander
*/
package org.openmolecules.chem.conf.gen;
import com.actelion.research.calc.ThreadMaster;
import com.actelion.research.chem.*;
import com.actelion.research.chem.conf.Conformer;
import com.actelion.research.chem.conf.TorsionDB;
import com.actelion.research.chem.conf.VDWRadii;
import com.actelion.research.util.DoubleFormat;
import com.actelion.research.util.IntArrayComparator;
import org.openmolecules.chem.conf.so.ConformationSelfOrganizer;
import org.openmolecules.chem.conf.so.SelfOrganizedConformer;
import java.util.Arrays;
import java.util.Random;
import java.util.TreeMap;
/**
* This class generates 3D-conformers of a given molecule using the following strategy:
* All rotatable, non-ring bonds are determined.
* Fragments separated by rotatable bonds are considered rigid, but there may be more than one possible
* fragment conformer, e.g. chair- and boat conformers of a saturated 6-membered ring.
* These atom coordinate sets of rigid fragments are handed out by a dedicated RigidFragmentProvider instance,
* which either generates them using a self organization algorithm, or which takes it from a cache.
* For every rotatable bond a list of preferred torsion angles is determined based on from a COD statistics
* of similar bond environments.
* For individual torsion values likelihoods are estimated based on frequency and atom collisions of vicinal fragments.
* A dedicated (systematic, biased or random) torsion set strategy delivers collision-free torsion sets, i.e. conformers.
*
* For generating conformers in multiple threads, every thread needs its own ConformerGenerator instance.
* If they use a RigidFragmentCache, then the cache is shared among all ConformerGenerators.
* Important: Input molecules should contain absolute stereo centers. If they contain undefined or ESR type '&' or 'or'
* stereo centers, then a ConformerGenerator randomly takes one of the possible stereo isomers and generates conformers
* for that. If you want conformers for all possible stereo isomers of a molecules with non-absolute stereo centers,
* you should use a StereoIsomerEnumerator to produce all possible stereo isomers and then produce conformers for every
* one of them. If half of a set of stereo isomers consists of the enantiomers of the other half, then it is advisable
* to generate conformes for one half only and to generate the second half by just mirroring the first halfs coordinates.
* To do that use option skipEnantiomers==true create a mirrored set of conformers, if isSkippingEnantiomers() of the
* StereoIsomerEnumerator returns true.
*/
public class ConformerGenerator {
public static final int STRATEGY_LIKELY_SYSTEMATIC = 1;
public static final int STRATEGY_PURE_RANDOM = 2;
public static final int STRATEGY_LIKELY_RANDOM = 3;
public static final int STRATEGY_ADAPTIVE_RANDOM = 4;
protected static final double VDW_TOLERANCE_HYDROGEN = 0.90; // factor on VDW radii for minimum tolerated non bound atom distances
protected static final double VDW_TOLERANCE_OTHER = 0.90; // factor on VDW radii for minimum tolerated non bound atom distances
private static final int ESCAPE_ANGLE = 8; // degrees to rotate two adjacent rotatable bonds to escape collisions
private static final int ESCAPE_STEPS = 3; // how often we apply this rotation trying to solve the collision
private static final double MIN_ESCAPE_GAIN_PER_STEP = 1.0;
// We try to translate arbitrary collision values into a kcal/mol energy scale
public static final double COLLISION_STRAIN_TO_ENERGY_FACTOR = 20;
private StereoMolecule mMolecule;
private TreeMap mBaseConformerMap;
private RotatableBond[] mRotatableBond;
private RigidFragment[] mRigidFragment;
private ConformationSelfOrganizer mSelfOrganizer;
private final RigidFragmentProvider mRigidFragmentProvider;
private TorsionSetStrategy mTorsionSetStrategy;
private TorsionSet mTorsionSet;
private final long mRandomSeed;
private long mTimeOut,mStopMillis;
private int mDisconnectedFragmentCount,mAllConformerCount,mReturnedConformerCount;
private boolean mUseSelfOrganizerIfAllFails,mIsDiagnosticsMode,mIsFinished;
private int[] mFragmentNo,mDisconnectedFragmentNo,mDisconnectedFragmentSize;
private boolean[][] mSkipCollisionCheck;
private final Random mRandom;
private ThreadMaster mThreadMaster;
private ConformerSetDiagnostics mDiagnostics;
/**
* Assuming that the given molecule has 2D-coordinates, this method
* converts all implicit hydrogen atoms into explicit ones by filling valences
* and adapting for atom charges. New hydrogen atoms receive new 2D-coordinates
* by equally locating them between those two neighbors with the widest angle between
* their bonds. Any stereo configurations deducible from 2D-coordinates are retained.
* @param mol
*/
public static void addHydrogenAtoms(StereoMolecule mol) {
// We may have parities but empty coordinates. In this case we need to protect parities.
int oldStereoHelperBits = mol.getHelperArrayStatus() & Molecule.cHelperBitsStereo;
mol.ensureHelperArrays(Molecule.cHelperNeighbours);
int[] implicitHydrogen = new int[mol.getAtoms()];
for (int atom=0; atom mStopMillis);
}
/**
* Fills all free valences of mol with explicit hydrogens and tries to
* create a reasonable conformer by starting with the most likely torsion set.
* If there are collisions, then less likely torsions are tried to find
* a collision free conformer. If it succeeds, mol receives the modified
* atom coordinates and mol is returned. If the conformer generation fails,
* then null is returned. The torsion strategy used is STRATEGY_ADAPTIVE_RANDOM.
* New 3D-coordinates correctly reflect E/Z and R/S bond/atom parities.
* This is a convenience method that does not require any initialization.
* @param mol the molecule that receive new 3D coordinates in place
* @return original molecule with new 3D-coordinates or null
*/
public StereoMolecule getOneConformerAsMolecule(StereoMolecule mol) {
Conformer conformer = getOneConformer(mol);
return (conformer == null) ? null : conformer.toMolecule(mol);
}
/**
* Fills all free valences of mol with explicit hydrogens and tries to
* create a reasonable conformer by starting with the most likely torsion set.
* If there are collisions, then less likely torsions are tried to find
* a collision free conformer. If this fails, then null is returned.
* The torsion strategy used is STRATEGY_ADAPTIVE_RANDOM.
* New 3D-coordinates correctly reflect E/Z and R/S bond/atom parities.
* This is a convenience method that does not require any initialization.
* @param mol the molecule from which to create the conformer
*/
public Conformer getOneConformer(StereoMolecule mol) {
if (!initialize(mol, false))
return null;
if (mRotatableBond != null) {
mTorsionSetStrategy = new TorsionSetStrategyAdaptiveRandom(this, true, true, mRandomSeed);
mTorsionSetStrategy.setMaxTotalCount(400);
mBaseConformerMap = new TreeMap<>(new IntArrayComparator());
return getNextConformer();
}
else {
ConformationSelfOrganizer sampler = new ConformationSelfOrganizer(mol, true);
sampler.setThreadMaster(mThreadMaster);
sampler.setStopTime(mStopMillis);
Conformer conformer = sampler.generateOneConformer(mRandomSeed);
separateDisconnectedFragments(conformer);
conformer.setName("SO#1");
return conformer;
}
}
/**
* Don't call this method directly. Rather call initializeConformers() !!!
* Adds implicit hydrogens to the molecule and determines all rotatable bonds,
* which are not part of a ring. Generates rigid fragments between rotatable bonds.
* The base conformer is constructed by connecting all rigid fragments using the
* most frequent torsions. Atoms of different fragments in the base conformer may
* collide. In order to obtain collision free conformers choose a TorsionStrategy
* and call getNextConformer() at least once.
* @param mol
* @param use60degreeSteps use 60 degree steps for every rotatable bond instead of torsion DB
*/
protected boolean initialize(StereoMolecule mol, boolean use60degreeSteps) {
applyTimeOut();
mSelfOrganizer = null;
mol.ensureHelperArrays(Molecule.cHelperNeighbours);
for (int atom=0; atom mol.getMaxValence(atom))
return false;
addHydrogenAtoms(mol);
// we need to protect explicit hydrogens in the fragments that we create from mol
mol.setHydrogenProtection(true);
int[] atomParity = null;
int[] bondParity = null;
boolean[] atomParityIsPseudo = null;
boolean[] bondParityIsPseudo = null;
// if we have parities and no atom coordinates, parities cannot be correctly recreated
// by the Canonizer and, thus, need to be cached and copied back after the symmetry detection.
if ((mol.getHelperArrayStatus() & Molecule.cHelperBitParities) != 0) {
atomParity = new int[mol.getAtoms()];
atomParityIsPseudo = new boolean[mol.getAtoms()];
for (int atom=0; atom
Integer.compare(b2.getSmallerSideAtoms().length, b1.getSmallerSideAtoms().length) );
if (mIsDiagnosticsMode)
mDiagnostics = new ConformerSetDiagnostics(this);
// TODO this is actually only used with random conformers. Using a conformer mode
// may save some time, if systematic conformers are created.
initializeCollisionCheck();
return true;
}
/**
* After calling initializeConformers() this method returns the number of rotatable bonds,
* which are used to separate the molecule into rigid fragments.
* @return
*/
public int getRotatableBondCount() {
return mRotatableBond == null ? 0 : mRotatableBond.length;
}
public TreeMap getBaseConformerMap() {
return mBaseConformerMap;
}
public TorsionSetStrategy getTorsionSetStrategy() {
return mTorsionSetStrategy;
}
public BaseConformer getBaseConformer(int[] fragmentPermutation) {
BaseConformer baseConformer = mBaseConformerMap.get(fragmentPermutation);
if (baseConformer != null)
return baseConformer;
baseConformer = new BaseConformer(mMolecule, mRigidFragment, mRotatableBond, fragmentPermutation, mRandom);
//printDebugConformers(baseConformer);
mBaseConformerMap.put(fragmentPermutation.clone(), baseConformer);
return baseConformer;
}
/**
* Creates the next random, likely or systematic new(!) conformer of the molecule
* that was passed when calling initializeConformers(). A new conformer is one,
* whose combination of torsion angles was not used in a previous conformer
* created by this function since the last call of initializeConformers().
* If parameter mol is null, then a compact copy of the original molecule with the new
* coordinates is returned. You may pass the original molecule or a copy of it to
* recycle the original molecule to receive new 3D coordinates.
* Every call of this method creates a new collision-free conformer until the employed torsion set
* strategy decides that it cannot generate any more suitable torsion sets.
* @param mol null or molecule used during initialization or a copy of it
* @return conformer or null, if all/maximum torsion permutations have been tried
*/
public StereoMolecule getNextConformerAsMolecule(StereoMolecule mol) {
Conformer conformer = getNextConformer();
return (conformer == null) ? null : conformer.toMolecule(mol);
}
public Conformer getNextConformer() {
return getNextConformer(null);
}
/**
* Creates the next random, likely or systematic new(!) conformer of the molecule
* that was passed when calling initializeConformers(). A new conformer is one,
* whose combination of torsion angles was not used in a previous conformer
* created by this function since the last call of initializeConformers().
* Every call of this method creates a new collision-free conformer until the employed torsion set
* strategy decides that it cannot generate any more suitable torsion sets.
* @param torsionSetHolder : will contain the TorsionSet that gave rise to the conformer.
* @return conformer or null, if all/maximum torsion permutations have been tried
*/
public Conformer getNextConformer(TorsionSet[] torsionSetHolder) {
if (mRotatableBond == null && mSelfOrganizer == null)
return null;
if (mSelfOrganizer != null) {
SelfOrganizedConformer conformer = mSelfOrganizer.getNextConformer();
if (conformer != null) {
separateDisconnectedFragments(conformer);
mReturnedConformerCount++;
conformer.setName("SO#"+(++mAllConformerCount));
return conformer;
}
return null;
}
if (mIsFinished)
return null;
// create a base conformer from first set of fragments and calculate torsion likelihoods
if (mBaseConformerMap.isEmpty())
getBaseConformer(new int[mRigidFragment.length]);
mTorsionSet = mTorsionSetStrategy.getNextTorsionSet(mTorsionSet, mDiagnostics);
while (mTorsionSet != null && !mustStop()) {
BaseConformer baseConformer = getBaseConformer(mTorsionSet.getConformerIndexes());
if (mTorsionSet.getConformer() == null) {
mTorsionSet.setConformer(baseConformer.deriveConformer(mTorsionSet.getTorsionIndexes(), "#" + (++mAllConformerCount)));
if (mIsDiagnosticsMode)
mDiagnostics.addNew(mTorsionSet);
}
// If the torsionSet has already a collision value, then it is a second choice torsion set
// with a collision value below the tolerance. No need to check or fix again.
if (mTorsionSet.getCollisionStrainSum() == 0.0) {
calculateCollision(mTorsionSet, mTorsionSet.getConformer());
if (mTorsionSet.getCollisionStrainSum() != 0.0)
tryFixCollisions(baseConformer, mTorsionSet);
if (mIsDiagnosticsMode) {
mDiagnostics.get(mTorsionSet).setConformer(baseConformer, mTorsionSet.getConformer());
mDiagnostics.get(mTorsionSet).setCollisionStrain(mTorsionSet.getCollisionStrainSum());
}
}
if (mTorsionSet.getCollisionStrainSum() > mTorsionSetStrategy.calculateCollisionTolerance()) {
mTorsionSet = mTorsionSetStrategy.getNextTorsionSet(mTorsionSet, mDiagnostics);
if (mTorsionSet != null || mReturnedConformerCount != 0)
continue;
if (mUseSelfOrganizerIfAllFails) {
// We couldn't create torsion strategy based conformers: switch to self organizer!
mSelfOrganizer = new ConformationSelfOrganizer(mMolecule, true);
mSelfOrganizer.setThreadMaster(mThreadMaster);
mSelfOrganizer.setStopTime(mStopMillis);
mSelfOrganizer.initializeConformers(mRandomSeed, -1);
SelfOrganizedConformer conformer = mSelfOrganizer.getNextConformer();
if (conformer != null) {
separateDisconnectedFragments(conformer);
mReturnedConformerCount++;
conformer.setName("SO#"+(++mAllConformerCount));
return conformer;
}
}
// we didn't get any torsion set that didn't collide; take the best we had
mTorsionSet = mTorsionSetStrategy.getBestCollidingTorsionIndexes();
mIsFinished = true; // we are finished with conformers
}
if (mTorsionSet != null) {
separateDisconnectedFragments(mTorsionSet.getConformer());
mTorsionSet.setUsed();
mReturnedConformerCount++;
if(torsionSetHolder != null)
torsionSetHolder[0] = new TorsionSet(mTorsionSet);
if (mIsDiagnosticsMode)
mDiagnostics.get(mTorsionSet).setSuccess(true);
return mTorsionSet.getConformer();
}
// This poses the danger to produce highly strained unrealistic conformers, e.g. for impossible compounds...
// else if (mReturnedConformerCount == 0) {
// // We couldn't create torsion strategy based conformers: try creating one conformer with self organizer!
// ConformationSelfOrganizer sampler = new ConformationSelfOrganizer(mMolecule, true);
// sampler.setThreadMaster(mThreadMaster);
// sampler.setStopTime(mStopMillis);
// Conformer conformer = sampler.generateOneConformer(mRandomSeed);
// separateDisconnectedFragments(conformer);
// mReturnedConformerCount++;
// conformer.setName("SO#1");
// return conformer;
// }
}
return null;
}
/*private void printDebugConformers(BaseConformer bc) {
int degreesA = bc.getBondTorsion(mRotatableBond[0].getBond());
int degreesB = bc.getBondTorsion(mRotatableBond[1].getBond());
System.out.println("Startangles A:"+degreesA+" B:"+degreesB);
System.out.println("idcode\tidcoords\tdegrees A\tdegrees B");
for (int degrees=0; degrees<100; degrees+=20) {
Conformer co = new Conformer(bc);
bc.rotateTo(co, mRotatableBond[0], (short)(degreesA + degrees));
Canonizer ca = new Canonizer(co.toMolecule(null));
System.out.println(ca.getIDCode() + "\t" + ca.getEncodedCoordinates() + "\t" + degrees +"\t0");
}
for (int degrees=0; degrees<100; degrees+=20) {
Conformer co = new Conformer(bc);
bc.rotateTo(co, mRotatableBond[1], (short)(degreesB + degrees));
Canonizer ca = new Canonizer(co.toMolecule(null));
System.out.println(ca.getIDCode() + "\t" + ca.getEncodedCoordinates() + "\t0\t" + degrees);
}
}*/
/**
* @return count of valid delivered conformers
*/
public int getConformerCount() {
return mReturnedConformerCount;
}
/**
* Calculates the potential count of conformers by multiplying degrees of freedom
* (torsions per rotatable bond & rigid fragment multiplicities).
* Cannot be called before calling initializeConformers().
* @return
*/
public int getPotentialConformerCount() {
return (mTorsionSetStrategy == null) ? 1 : mTorsionSetStrategy.getPermutationCount();
}
/**
* If a molecule has at least one rotatable bond if all permutations
* of torsions collide beyond a tolerated strain, then the standard
* behaviour of this class is to return that clashing conformer with
* the lowest strain.
* If passing true to this method, the ConformerGenerator will use
* the ConformerSelfOrganizer in these cases to generate conformers.
* getNextConformer will then deliver conformers until the self organization
* fails to create new conformers.
* @param b
*/
public void setUseSelfOrganizerIfAllFails(boolean b) {
mUseSelfOrganizerIfAllFails = b;
}
/**
* One of the initializeConformers() methods needs to be called, before getting individual
* conformers of the same molecule by getNextConformer().
* Open valences of the passed molecule are filled with hydrogen atoms.
* The passed molecule may repeatedly be used as container for a new conformer's atom
* coordinates, if it is passed as parameter to getNextConformer().
* This method uses the STRATEGY_LIKELY_RANDOM strategy with a maximum of 100.000 distinct
* torsion sets and uses torsions from crystallographic data.
* @param mol will be saturated with hydrogen atoms
* @return false if there is a structure problem
*/
public boolean initializeConformers(StereoMolecule mol) {
return initializeConformers(mol, STRATEGY_LIKELY_RANDOM, 100000, false);
}
/**
* One of the initializeConformers() methods needs to be called, before getting individual
* conformers of the same molecule by getNextConformer().
* Open valences of the passed molecule are filled with hydrogen atoms.
* The passed molecule may repeatedly be used as container for a new conformer's atom
* coordinates, if it is passed as parameter to getNextConformer().
* @param mol will be saturated with hydrogen atoms
* @param strategy one of the STRATEGY_ constants
* @param maxTorsionSets maximum number of distinct torsion sets the strategy will try (default 100000)
* @param use60degreeSteps use 60 degree steps for every rotatable bond instead of torsion DB
* @return false if there is a structure problem
*/
public boolean initializeConformers(StereoMolecule mol, int strategy, int maxTorsionSets, boolean use60degreeSteps) {
if (!initialize(mol, use60degreeSteps))
return false;
if (mRotatableBond == null) {
mSelfOrganizer = new ConformationSelfOrganizer(mol, true);
mSelfOrganizer.setThreadMaster(mThreadMaster);
mSelfOrganizer.setStopTime(mStopMillis);
mSelfOrganizer.initializeConformers(mRandomSeed, -1);
}
else {
mBaseConformerMap = new TreeMap<>(new IntArrayComparator());
switch(strategy) {
case STRATEGY_PURE_RANDOM:
mTorsionSetStrategy = new TorsionSetStrategyRandom(this, false, mRandomSeed);
break;
case STRATEGY_LIKELY_RANDOM:
mTorsionSetStrategy = new TorsionSetStrategyRandom(this, true, mRandomSeed);
break;
case STRATEGY_ADAPTIVE_RANDOM:
mTorsionSetStrategy = new TorsionSetStrategyAdaptiveRandom(this, true, true, mRandomSeed);
break;
case STRATEGY_LIKELY_SYSTEMATIC:
mTorsionSetStrategy = new TorsionSetStrategyLikelySystematic(this);
break;
}
mTorsionSetStrategy.setMaxTotalCount(maxTorsionSets);
}
return true;
}
public RotatableBond[] getRotatableBonds() {
return mRotatableBond;
}
public RigidFragment[] getRigidFragments() {
return mRigidFragment;
}
/**
* Moves disconnected fragments along Z-axis such that there is an
* empty z-space SEPARATION_DISTANCE thick between the fragments.
* @param conformer
*/
private void separateDisconnectedFragments(Conformer conformer) {
final double SEPARATION_DISTANCE = 3.0;
if (mDisconnectedFragmentCount > 1) {
double[] meanX = new double[mDisconnectedFragmentCount];
double[] meanY = new double[mDisconnectedFragmentCount];
double[] minZ = new double[mDisconnectedFragmentCount];
double[] maxZ = new double[mDisconnectedFragmentCount];
for (int i=0; i conformer.getZ(atom))
minZ[mDisconnectedFragmentNo[atom]] = conformer.getZ(atom);
if (maxZ[mDisconnectedFragmentNo[atom]] < conformer.getZ(atom))
maxZ[mDisconnectedFragmentNo[atom]] = conformer.getZ(atom);
}
for (int i=0; i TorsionSetStrategy.MAX_COLLISION_STRAIN)
return false;
Conformer conformer = null;
Conformer localBest = null;
Conformer globalBest = null;
double bestCollisionStrain = Double.MAX_VALUE;
double origCollisionStrainSum = torsionSet.getCollisionStrainSum();
for (int f1=1; f1 MIN_ESCAPE_GAIN_PER_STEP
&& mTorsionSetStrategy.getBondsBetweenFragments(f1, f2).length == 2) {
int[] rbIndex = mTorsionSetStrategy.getBondsBetweenFragments(f1, f2);
int[] startTorsion = new int[2];
for (int i=0; i<2; i++) {
RotatableBond rotatableBond = mRotatableBond[rbIndex[i]];
startTorsion[i] = torsionSet.getConformer().getBondTorsion(rotatableBond.getBond());
// short[] torsionRange = rotatableBond.getDefaultTorsionRanges()[torsionSet.getTorsionIndexes()[rbIndex[i]]];
}
int[] torsionDif = new int[2];
for (int r1=-1; r1<=1; r1+=2) {
torsionDif[0] = r1 * ESCAPE_ANGLE;
for (int r2=-1; r2<=1; r2+=2) {
torsionDif[1] = r2 * ESCAPE_ANGLE;
double collisionStrain = origCollisionStrainMatrix[f1][f2];
for (int step=1; step<=ESCAPE_STEPS; step++) {
if (conformer == null)
conformer = new Conformer(torsionSet.getConformer());
else
conformer.copyFrom(torsionSet.getConformer());
for (int i=0; i<2; i++)
baseConformer.rotateTo(conformer, mRotatableBond[rbIndex[i]], (short)(startTorsion[i] + step * torsionDif[i]));
double strain = calculateCollisionStrain(conformer, mRigidFragment[f1], mRigidFragment[f2]);
if (strain < collisionStrain - MIN_ESCAPE_GAIN_PER_STEP) {
collisionStrain = strain;
if (localBest == null)
localBest = new Conformer(conformer);
else
localBest.copyFrom(conformer);
// not enough collision strain left for correction
if (collisionStrain < MIN_ESCAPE_GAIN_PER_STEP)
break;
}
else {
break;
}
}
if (collisionStrain < origCollisionStrainMatrix[f1][f2]
&& collisionStrain < bestCollisionStrain) {
bestCollisionStrain = collisionStrain;
if (globalBest == null)
globalBest = new Conformer(localBest);
else
globalBest.copyFrom(localBest);
}
}
}
}
}
}
}
if (globalBest == null)
return false;
calculateCollision(torsionSet, globalBest);
if (torsionSet.getCollisionStrainSum() >= origCollisionStrainSum) {
// local improvement causes worsening somewhere else
torsionSet.setCollisionStrain(origCollisionStrainSum, origCollisionStrainMatrix);
return false;
}
torsionSet.getConformer().copyFrom(globalBest);
return true;
}
private double calculateCollisionStrain(Conformer conformer, RigidFragment f1, RigidFragment f2) {
double collisionStrainSum = 0;
for (int i=0; i