Merge branch 'master' into gayberne

platforms/reference/src/SimTKReference/ReferenceCustomTorsionIxn.cpp

@@ -38,20 +38,19 @@ using namespace OpenMM;
    --------------------------------------------------------------------------------------- */
 
 ReferenceCustomTorsionIxn::ReferenceCustomTorsionIxn(const Lepton::CompiledExpression& energyExpression,
-        const Lepton::CompiledExpression& forceExpression, const vector<string>& parameterNames, map<string, double> globalParameters) :
-        energyExpression(energyExpression), forceExpression(forceExpression), usePeriodic(false) {
-
-    energyTheta = ReferenceForce::getVariablePointer(this->energyExpression, "theta");
-    forceTheta = ReferenceForce::getVariablePointer(this->forceExpression, "theta");
+        const Lepton::CompiledExpression& forceExpression, const vector<string>& parameterNames, map<string, double> globalParameters,
+        const vector<Lepton::CompiledExpression> energyParamDerivExpressions) :
+        energyExpression(energyExpression), forceExpression(forceExpression), usePeriodic(false), energyParamDerivExpressions(energyParamDerivExpressions) {
+    expressionSet.registerExpression(this->energyExpression);
+    expressionSet.registerExpression(this->forceExpression);
+    for (int i = 0; i < this->energyParamDerivExpressions.size(); i++)
+        expressionSet.registerExpression(this->energyParamDerivExpressions[i]);
+    thetaIndex = expressionSet.getVariableIndex("theta");
     numParameters = parameterNames.size();
-    for (int i = 0; i < (int) numParameters; i++) {
-        energyParams.push_back(ReferenceForce::getVariablePointer(this->energyExpression, parameterNames[i]));
-        forceParams.push_back(ReferenceForce::getVariablePointer(this->forceExpression, parameterNames[i]));
-    }
-    for (map<string, double>::const_iterator iter = globalParameters.begin(); iter != globalParameters.end(); ++iter) {
-        ReferenceForce::setVariable(ReferenceForce::getVariablePointer(this->energyExpression, iter->first), iter->second);
-        ReferenceForce::setVariable(ReferenceForce::getVariablePointer(this->forceExpression, iter->first), iter->second);
-    }
+    for (int i = 0; i < (int) numParameters; i++)
+        torsionParamIndex.push_back(expressionSet.getVariableIndex(parameterNames[i]));
+    for (map<string, double>::const_iterator iter = globalParameters.begin(); iter != globalParameters.end(); ++iter)
+        expressionSet.setVariable(expressionSet.getVariableIndex(iter->first), iter->second);
 }
 
 /**---------------------------------------------------------------------------------------
@@ -86,18 +85,10 @@ void ReferenceCustomTorsionIxn::calculateBondIxn(int* atomIndices,
                                                 vector<RealVec>& atomCoordinates,
                                                 RealOpenMM* parameters,
                                                 vector<RealVec>& forces,
-                                                RealOpenMM* totalEnergy) const {
-
-   static const std::string methodName = "\nReferenceCustomTorsionIxn::calculateTorsionIxn";
-
-   static const RealOpenMM zero        = 0.0;
-   static const RealOpenMM one         = 1.0;
-
+                                                RealOpenMM* totalEnergy, double* energyParamDerivs) {
    RealOpenMM deltaR[3][ReferenceForce::LastDeltaRIndex];
-   for (int i = 0; i < numParameters; i++) {
-       ReferenceForce::setVariable(energyParams[i], parameters[i]);
-       ReferenceForce::setVariable(forceParams[i], parameters[i]);
-   }
+   for (int i = 0; i < numParameters; i++)
+       expressionSet.setVariable(torsionParamIndex[i], parameters[i]);
 
    // ---------------------------------------------------------------------------------------
 
@@ -130,8 +121,7 @@ void ReferenceCustomTorsionIxn::calculateBondIxn(int* atomIndices,
    RealOpenMM dotDihedral;
    RealOpenMM signOfAngle;
    RealOpenMM angle = getDihedralAngleBetweenThreeVectors(deltaR[0], deltaR[1], deltaR[2], crossProduct, &dotDihedral, deltaR[0], &signOfAngle, 1);
-   ReferenceForce::setVariable(energyTheta, angle);
-   ReferenceForce::setVariable(forceTheta, angle);
+   expressionSet.setVariable(thetaIndex, angle);
 
    // evaluate delta angle, dE/d(angle)
 
@@ -174,6 +164,11 @@ void ReferenceCustomTorsionIxn::calculateBondIxn(int* atomIndices,
       forces[atomDIndex][ii] += internalF[3][ii];
    }
 
+   // Record parameter derivatives.
+
+   for (int i = 0; i < energyParamDerivExpressions.size(); i++)
+       energyParamDerivs[i] += energyParamDerivExpressions[i].evaluate();
+
    // accumulate energies
 
    if (totalEnergy != NULL)

platforms/reference/src/SimTKReference/ReferenceHarmonicBondIxn.cpp

@@ -74,7 +74,7 @@ void ReferenceHarmonicBondIxn::calculateBondIxn(int* atomIndices,
                                                 vector<RealVec>& atomCoordinates,
                                                 RealOpenMM* parameters,
                                                 vector<RealVec>& forces,
-                                                RealOpenMM* totalEnergy) const {
+                                                RealOpenMM* totalEnergy, double* energyParamDerivs) {
 
    static const std::string methodName = "\nReferenceHarmonicBondIxn::calculateBondIxn";
 

platforms/reference/src/SimTKReference/ReferenceLJCoulomb14.cpp

 
-/* Portions copyright (c) 2006 Stanford University and Simbios.
+/* Portions copyright (c) 2006-2016 Stanford University and Simbios.
  * Contributors: Pande Group
  *
  * Permission is hereby granted, free of charge, to any person obtaining
@@ -81,7 +81,7 @@ ReferenceLJCoulomb14::~ReferenceLJCoulomb14() {
 
 void ReferenceLJCoulomb14::calculateBondIxn(int* atomIndices, vector<RealVec>& atomCoordinates,
                                      RealOpenMM* parameters, vector<RealVec>& forces,
-                                     RealOpenMM* totalEnergy) const {
+                                     RealOpenMM* totalEnergy, double* energyParamDerivs) {
 
    static const std::string methodName = "\nReferenceLJCoulomb14::calculateBondIxn";
 

platforms/reference/src/SimTKReference/ReferenceLJCoulombIxn.cpp

@@ -420,6 +420,7 @@ void ReferenceLJCoulombIxn::calculateEwaldIxn(int numberOfAtoms, vector<RealVec>
     // Now subtract off the exclusions, since they were implicitly included in the reciprocal space sum.
 
     RealOpenMM totalExclusionEnergy = 0.0f;
+    const double TWO_OVER_SQRT_PI = 2/sqrt(PI_M);
     for (int i = 0; i < numberOfAtoms; i++)
         for (set<int>::const_iterator iter = exclusions[i].begin(); iter != exclusions[i].end(); ++iter) {
             if (*iter > i) {
@@ -446,12 +447,15 @@ void ReferenceLJCoulombIxn::calculateEwaldIxn(int numberOfAtoms, vector<RealVec>
                    // accumulate energies
 
                    realSpaceEwaldEnergy = (RealOpenMM) (ONE_4PI_EPS0*atomParameters[ii][QIndex]*atomParameters[jj][QIndex]*inverseR*erf(alphaR));
+               }
+               else {
+                   realSpaceEwaldEnergy = (RealOpenMM) (alphaEwald*TWO_OVER_SQRT_PI*ONE_4PI_EPS0*atomParameters[ii][QIndex]*atomParameters[jj][QIndex]);
+               }
 
-                   totalExclusionEnergy += realSpaceEwaldEnergy;
-                   if (energyByAtom) {
-                       energyByAtom[ii] -= realSpaceEwaldEnergy;
-                       energyByAtom[jj] -= realSpaceEwaldEnergy;
-                   }
+               totalExclusionEnergy += realSpaceEwaldEnergy;
+               if (energyByAtom) {
+                   energyByAtom[ii] -= realSpaceEwaldEnergy;
+                   energyByAtom[jj] -= realSpaceEwaldEnergy;
                }
             }
         }

platforms/reference/src/SimTKReference/ReferenceProperDihedralBond.cpp

@@ -75,7 +75,7 @@ void ReferenceProperDihedralBond::calculateBondIxn(int* atomIndices,
                                                    vector<RealVec>& atomCoordinates,
                                                    RealOpenMM* parameters,
                                                    vector<RealVec>& forces,
-                                                   RealOpenMM* totalEnergy) const {
+                                                   RealOpenMM* totalEnergy, double* energyParamDerivs) {
 
    static const std::string methodName = "\nReferenceProperDihedralBond::calculateBondIxn";
 

platforms/reference/src/SimTKReference/ReferenceRbDihedralBond.cpp

@@ -73,7 +73,7 @@ void ReferenceRbDihedralBond::calculateBondIxn(int* atomIndices,
                                                vector<RealVec>& atomCoordinates,
                                                RealOpenMM* parameters,
                                                vector<RealVec>& forces,
-                                               RealOpenMM* totalEnergy) const {
+                                               RealOpenMM* totalEnergy, double* energyParamDerivs) {
 
    static const std::string methodName = "\nReferenceRbDihedralBond::calculateBondIxn";
 

platforms/reference/src/SimTKReference/SimTKOpenMMUtilities.cpp

@@ -383,8 +383,11 @@ void SimTKOpenMMUtilities::createCheckpoint(std::ostream& stream) {
 
 void SimTKOpenMMUtilities::loadCheckpoint(std::istream& stream) {
     stream.read((char*) &_randomNumberSeed, sizeof(uint32_t));
+    bool prevInitialized = _randomInitialized;
     stream.read((char*) &_randomInitialized, sizeof(bool));
     if (_randomInitialized) {
+        if (!prevInitialized)
+            init_gen_rand(0, sfmt);
         stream.read((char*) &nextGaussianIsValid, sizeof(bool));
         stream.read((char*) &nextGaussian, sizeof(RealOpenMM));
         sfmt.loadCheckpoint(stream);

plugins/amoeba/openmmapi/include/openmm/AmoebaMultipoleForce.h

@@ -147,11 +147,34 @@ public:
      */
     void setCutoffDistance(double distance);
 
+    /**
+     * Get the parameters to use for PME calculations.  If alpha is 0 (the default), these parameters are
+     * ignored and instead their values are chosen based on the Ewald error tolerance.
+     *
+     * @param[out] alpha   the separation parameter
+     * @param[out] nx      the number of grid points along the X axis
+     * @param[out] ny      the number of grid points along the Y axis
+     * @param[out] nz      the number of grid points along the Z axis
+     */
+    void getPMEParameters(double& alpha, int& nx, int& ny, int& nz) const;
+
+    /**
+     * Set the parameters to use for PME calculations.  If alpha is 0 (the default), these parameters are
+     * ignored and instead their values are chosen based on the Ewald error tolerance.
+     *
+     * @param alpha   the separation parameter
+     * @param nx      the number of grid points along the X axis
+     * @param ny      the number of grid points along the Y axis
+     * @param nz      the number of grid points along the Z axis
+     */
+    void setPMEParameters(double alpha, int nx, int ny, int nz);
+
     /**
      * Get the Ewald alpha parameter.  If this is 0 (the default), a value is chosen automatically
      * based on the Ewald error tolerance.
      *
      * @return the Ewald alpha parameter
+     * @deprecated This method exists only for backward compatibility.  Use getPMEParameters() instead.
      */
     double getAEwald() const;
 
@@ -160,6 +183,7 @@ public:
      * based on the Ewald error tolerance.
      *
      * @param aewald alpha parameter
+     * @deprecated This method exists only for backward compatibility.  Use setPMEParameters() instead.
      */
     void setAEwald(double aewald);
 
@@ -175,6 +199,7 @@ public:
      * are chosen automatically based on the Ewald error tolerance.
      *
      * @return the PME grid dimensions
+     * @deprecated This method exists only for backward compatibility.  Use getPMEParameters() instead.
      */
     void getPmeGridDimensions(std::vector<int>& gridDimension) const;
 
@@ -183,6 +208,7 @@ public:
      * are chosen automatically based on the Ewald error tolerance.
      *
      * @param gridDimension   the PME grid dimensions
+     * @deprecated This method exists only for backward compatibility.  Use setPMEParameters() instead.
      */
     void setPmeGridDimensions(const std::vector<int>& gridDimension);
 
@@ -344,7 +370,13 @@ public:
      * This can be overridden by explicitly setting an alpha parameter and grid dimensions to use.
      */
     void setEwaldErrorTolerance(double tol);
-
+    /**
+     * Get the fixed dipole moments of all particles in the global reference frame.
+     *
+     * @param context         the Context for which to get the fixed dipoles
+     * @param[out] dipoles    the fixed dipole moment of particle i is stored into the i'th element
+     */
+    void getLabFramePermanentDipoles(Context& context, std::vector<Vec3>& dipoles);
     /**
      * Get the induced dipole moments of all particles.
      *
@@ -353,6 +385,14 @@ public:
      */
     void getInducedDipoles(Context& context, std::vector<Vec3>& dipoles);
 
+    /**
+     * Get the total dipole moments (fixed plus induced) of all particles.
+     *
+     * @param context         the Context for which to get the total dipoles
+     * @param[out] dipoles    the total dipole moment of particle i is stored into the i'th element
+     */
+    void getTotalDipoles(Context& context, std::vector<Vec3>& dipoles);
+
     /**
      * Get the electrostatic potential.
      *
@@ -408,9 +448,8 @@ private:
     NonbondedMethod nonbondedMethod;
     PolarizationType polarizationType;
     double cutoffDistance;
-    double aewald;
-    int pmeBSplineOrder;
-    std::vector<int> pmeGridDimension;
+    double alpha;
+    int pmeBSplineOrder, nx, ny, nz;
     int mutualInducedMaxIterations;
     std::vector<double> extrapolationCoefficients;
 

plugins/amoeba/openmmapi/include/openmm/AmoebaVdwForce.h

@@ -9,7 +9,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors: Mark Friedrichs, Peter Eastman                                    *
  * Contributors:                                                              *
  *                                                                            *
@@ -183,13 +183,34 @@ public:
      */
     void getParticleExclusions(int particleIndex, std::vector<int>& exclusions) const;
 
+    /**
+     * Get the cutoff distance (in nm) being used for nonbonded interactions.  If the NonbondedMethod in use
+     * is NoCutoff, this value will have no effect.
+     *
+     * @return the cutoff distance, measured in nm
+     */
+
+    double getCutoffDistance() const;
+    
+    /**
+     * Set the cutoff distance (in nm) being used for nonbonded interactions.  If the NonbondedMethod in use
+     * is NoCutoff, this value will have no effect.
+     *
+     * @param distance    the cutoff distance, measured in nm
+     */
+    void setCutoffDistance(double distance);
+
     /**
      * Set the cutoff distance.
+     * 
+     * @deprecated This method exists only for backward compatibility.  Use setCutoffDistance() instead.
      */
     void setCutoff(double cutoff);
 
     /**
      * Get the cutoff distance.
+     * 
+     * @deprecated This method exists only for backward compatibility.  Use getCutoffDistance() instead.
      */
     double getCutoff() const;
 

plugins/amoeba/openmmapi/include/openmm/amoebaKernels.h

@@ -59,7 +59,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the AmoebaBondForce this kernel will be used for
      */
@@ -99,7 +99,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the AmoebaAngleForce this kernel will be used for
      */
@@ -139,7 +139,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the AmoebaInPlaneAngleForce this kernel will be used for
      */
@@ -179,7 +179,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the PiTorsionForce this kernel will be used for
      */
@@ -219,7 +219,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the StretchBendForce this kernel will be used for
      */
@@ -259,7 +259,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the OutOfPlaneBendForce this kernel will be used for
      */
@@ -299,7 +299,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the TorsionTorsionForce this kernel will be used for
      */
@@ -332,7 +332,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the MultipoleForce this kernel will be used for
      */
@@ -348,7 +348,9 @@ public:
      */
     virtual double execute(ContextImpl& context, bool includeForces, bool includeEnergy) = 0;
 
+    virtual void getLabFramePermanentDipoles(ContextImpl& context, std::vector<Vec3>& dipoles) = 0;
     virtual void getInducedDipoles(ContextImpl& context, std::vector<Vec3>& dipoles) = 0;
+    virtual void getTotalDipoles(ContextImpl& context, std::vector<Vec3>& dipoles) = 0;
 
     virtual void getElectrostaticPotential(ContextImpl& context, const std::vector< Vec3 >& inputGrid,
                                            std::vector< double >& outputElectrostaticPotential) = 0;
@@ -364,7 +366,7 @@ public:
 
     /**
      * Get the parameters being used for PME.
-     * 
+     *
      * @param alpha   the separation parameter
      * @param nx      the number of grid points along the X axis
      * @param ny      the number of grid points along the Y axis
@@ -389,7 +391,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the GBSAOBCForce this kernel will be used for
      */
@@ -429,7 +431,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the GBSAOBCForce this kernel will be used for
      */
@@ -469,7 +471,7 @@ public:
 
     /**
      * Initialize the kernel.
-     * 
+     *
      * @param system     the System this kernel will be applied to
      * @param force      the GBSAOBCForce this kernel will be used for
      */

plugins/amoeba/openmmapi/include/openmm/internal/AmoebaMultipoleForceImpl.h

@@ -64,7 +64,7 @@ public:
 
     /**
      * Get the CovalentMap for an atom
-     * 
+     *
      * @param force                AmoebaMultipoleForce force reference
      * @param index                the index of the atom for which to set parameters
      * @param minCovalentIndex     minimum covalent index
@@ -76,13 +76,14 @@ public:
 
     /**
      * Get the covalent degree for the  CovalentEnd lists
-     * 
+     *
      * @param force                AmoebaMultipoleForce force reference
      * @param covalentDegree      covalent degrees for the CovalentEnd lists
      */
     static void getCovalentDegree(const AmoebaMultipoleForce& force, std::vector<int>& covalentDegree);
-
+    void getLabFramePermanentDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
     void getInducedDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
+    void getTotalDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
 
     void getElectrostaticPotential(ContextImpl& context, const std::vector< Vec3 >& inputGrid,
                                    std::vector< double >& outputElectrostaticPotential);
@@ -90,7 +91,7 @@ public:
     void getSystemMultipoleMoments(ContextImpl& context, std::vector< double >& outputMultipoleMoments);
     void updateParametersInContext(ContextImpl& context);
     void getPMEParameters(double& alpha, int& nx, int& ny, int& nz) const;
- 
+
 
 private:
     const AmoebaMultipoleForce& owner;

plugins/amoeba/openmmapi/src/AmoebaMultipoleForce.cpp

@@ -40,9 +40,7 @@ using std::string;
 using std::vector;
 
 AmoebaMultipoleForce::AmoebaMultipoleForce() : nonbondedMethod(NoCutoff), polarizationType(Mutual), pmeBSplineOrder(5), cutoffDistance(1.0), ewaldErrorTol(1e-4), mutualInducedMaxIterations(60),
-                                               mutualInducedTargetEpsilon(1.0e-02), scalingDistanceCutoff(100.0), electricConstant(138.9354558456), aewald(0.0) {
-    pmeGridDimension.resize(3);
-    pmeGridDimension[0] = pmeGridDimension[1] = pmeGridDimension[2];
+                                               mutualInducedTargetEpsilon(1.0e-02), scalingDistanceCutoff(100.0), electricConstant(138.9354558456), alpha(0.0), nx(0), ny(0), nz(0) {
     extrapolationCoefficients.push_back(-0.154);
     extrapolationCoefficients.push_back(0.017);
     extrapolationCoefficients.push_back(0.658);
@@ -81,12 +79,26 @@ void AmoebaMultipoleForce::setCutoffDistance(double distance) {
     cutoffDistance = distance;
 }
 
+void AmoebaMultipoleForce::getPMEParameters(double& alpha, int& nx, int& ny, int& nz) const {
+    alpha = this->alpha;
+    nx = this->nx;
+    ny = this->ny;
+    nz = this->nz;
+}
+
+void AmoebaMultipoleForce::setPMEParameters(double alpha, int nx, int ny, int nz) {
+    this->alpha = alpha;
+    this->nx = nx;
+    this->ny = ny;
+    this->nz = nz;
+}
+
 double AmoebaMultipoleForce::getAEwald() const { 
-    return aewald; 
+    return alpha; 
 } 
  
 void AmoebaMultipoleForce::setAEwald(double inputAewald) { 
-    aewald = inputAewald; 
+    alpha = inputAewald; 
 } 
  
 int AmoebaMultipoleForce::getPmeBSplineOrder() const { 
@@ -94,26 +106,18 @@ int AmoebaMultipoleForce::getPmeBSplineOrder() const {
 } 
  
 void AmoebaMultipoleForce::getPmeGridDimensions(std::vector<int>& gridDimension) const { 
-    if (gridDimension.size() < 3) {
+    if (gridDimension.size() < 3)
         gridDimension.resize(3);
-    }
-    if (pmeGridDimension.size() > 2) {
-        gridDimension[0] = pmeGridDimension[0];
-        gridDimension[1] = pmeGridDimension[1];
-        gridDimension[2] = pmeGridDimension[2];
-    } else {
-        gridDimension[0] = gridDimension[1] = gridDimension[2] = 0;
-    }
-    return;
+    gridDimension[0] = nx;
+    gridDimension[1] = ny;
+    gridDimension[2] = nz;
 } 
  
 void AmoebaMultipoleForce::setPmeGridDimensions(const std::vector<int>& gridDimension) {
-    pmeGridDimension.resize(3);
-    pmeGridDimension[0] = gridDimension[0];
-    pmeGridDimension[1] = gridDimension[1];
-    pmeGridDimension[2] = gridDimension[2];
-    return;
-} 
+    nx = gridDimension[0];
+    ny = gridDimension[1];
+    nz = gridDimension[2];
+}
 
 void AmoebaMultipoleForce::getPMEParametersInContext(const Context& context, double& alpha, int& nx, int& ny, int& nz) const {
     dynamic_cast<const AmoebaMultipoleForceImpl&>(getImplInContext(context)).getPMEParameters(alpha, nx, ny, nz);
@@ -143,13 +147,13 @@ void AmoebaMultipoleForce::setEwaldErrorTolerance(double tol) {
     ewaldErrorTol = tol;
 }
 
-int AmoebaMultipoleForce::addMultipole(double charge, const std::vector<double>& molecularDipole, const std::vector<double>& molecularQuadrupole, int axisType, 
+int AmoebaMultipoleForce::addMultipole(double charge, const std::vector<double>& molecularDipole, const std::vector<double>& molecularQuadrupole, int axisType,
                                        int multipoleAtomZ, int multipoleAtomX, int multipoleAtomY, double thole, double dampingFactor, double polarity) {
     multipoles.push_back(MultipoleInfo(charge, molecularDipole, molecularQuadrupole,  axisType, multipoleAtomZ,  multipoleAtomX, multipoleAtomY, thole, dampingFactor, polarity));
     return multipoles.size()-1;
 }
 
-void AmoebaMultipoleForce::getMultipoleParameters(int index, double& charge, std::vector<double>& molecularDipole, std::vector<double>& molecularQuadrupole, 
+void AmoebaMultipoleForce::getMultipoleParameters(int index, double& charge, std::vector<double>& molecularDipole, std::vector<double>& molecularQuadrupole,
                                                   int& axisType, int& multipoleAtomZ, int& multipoleAtomX, int& multipoleAtomY, double& thole, double& dampingFactor, double& polarity) const {
     charge                      = multipoles[index].charge;
 
@@ -179,7 +183,7 @@ void AmoebaMultipoleForce::getMultipoleParameters(int index, double& charge, std
     polarity                    = multipoles[index].polarity;
 }
 
-void AmoebaMultipoleForce::setMultipoleParameters(int index, double charge, const std::vector<double>& molecularDipole, const std::vector<double>& molecularQuadrupole, 
+void AmoebaMultipoleForce::setMultipoleParameters(int index, double charge, const std::vector<double>& molecularDipole, const std::vector<double>& molecularQuadrupole,
                                                   int axisType, int multipoleAtomZ, int multipoleAtomX, int multipoleAtomY, double thole, double dampingFactor, double polarity) {
 
     multipoles[index].charge                      = charge;
@@ -246,6 +250,14 @@ void AmoebaMultipoleForce::getInducedDipoles(Context& context, vector<Vec3>& dip
     dynamic_cast<AmoebaMultipoleForceImpl&>(getImplInContext(context)).getInducedDipoles(getContextImpl(context), dipoles);
 }
 
+void AmoebaMultipoleForce::getLabFramePermanentDipoles(Context& context, vector<Vec3>& dipoles) {
+    dynamic_cast<AmoebaMultipoleForceImpl&>(getImplInContext(context)).getLabFramePermanentDipoles(getContextImpl(context), dipoles);
+}
+
+void AmoebaMultipoleForce::getTotalDipoles(Context& context, vector<Vec3>& dipoles) {
+    dynamic_cast<AmoebaMultipoleForceImpl&>(getImplInContext(context)).getTotalDipoles(getContextImpl(context), dipoles);
+}
+
 void AmoebaMultipoleForce::getElectrostaticPotential(const std::vector< Vec3 >& inputGrid, Context& context, std::vector< double >& outputElectrostaticPotential) {
     dynamic_cast<AmoebaMultipoleForceImpl&>(getImplInContext(context)).getElectrostaticPotential(getContextImpl(context), inputGrid, outputElectrostaticPotential);
 }

plugins/amoeba/openmmapi/src/AmoebaMultipoleForceImpl.cpp

@@ -61,7 +61,7 @@ void AmoebaMultipoleForceImpl::initialize(ContextImpl& context) {
         double cutoff = owner.getCutoffDistance();
         if (cutoff > 0.5*boxVectors[0][0] || cutoff > 0.5*boxVectors[1][1] || cutoff > 0.5*boxVectors[2][2])
             throw OpenMMException("AmoebaMultipoleForce: The cutoff distance cannot be greater than half the periodic box size.");
-    }   
+    }
 
     double quadrupoleValidationTolerance = 1.0e-05;
     for (int ii = 0; ii < system.getNumParticles(); ii++) {
@@ -170,7 +170,7 @@ void AmoebaMultipoleForceImpl::getCovalentRange(const AmoebaMultipoleForce& forc
                *maxCovalentIndex = covalentList[ii];
             }
         }
-    }   
+    }
     return;
 }
 
@@ -179,14 +179,22 @@ void AmoebaMultipoleForceImpl::getCovalentDegree(const AmoebaMultipoleForce& for
     const int* CovalentDegrees = AmoebaMultipoleForceImpl::getCovalentDegrees();
     for (unsigned int kk = 0; kk < AmoebaMultipoleForce::CovalentEnd; kk++) {
         covalentDegree[kk] = CovalentDegrees[kk];
-    }   
+    }
     return;
 }
 
+void AmoebaMultipoleForceImpl::getLabFramePermanentDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
+    kernel.getAs<CalcAmoebaMultipoleForceKernel>().getLabFramePermanentDipoles(context, dipoles);
+}
+
 void AmoebaMultipoleForceImpl::getInducedDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
     kernel.getAs<CalcAmoebaMultipoleForceKernel>().getInducedDipoles(context, dipoles);
 }
 
+void AmoebaMultipoleForceImpl::getTotalDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
+    kernel.getAs<CalcAmoebaMultipoleForceKernel>().getTotalDipoles(context, dipoles);
+}
+
 void AmoebaMultipoleForceImpl::getElectrostaticPotential(ContextImpl& context, const std::vector< Vec3 >& inputGrid,
                                                          std::vector< double >& outputElectrostaticPotential) {
     kernel.getAs<CalcAmoebaMultipoleForceKernel>().getElectrostaticPotential(context, inputGrid, outputElectrostaticPotential);

plugins/amoeba/openmmapi/src/AmoebaVdwForce.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors:                                                                   *
  * Contributors:                                                              *
  *                                                                            *
@@ -102,12 +102,20 @@ void AmoebaVdwForce::getParticleExclusions(int particleIndex, std::vector< int >
 
 }
 
-void AmoebaVdwForce::setCutoff(double inputCutoff) {
+double AmoebaVdwForce::getCutoffDistance() const {
+    return cutoff;
+}
+
+void AmoebaVdwForce::setCutoffDistance(double inputCutoff) {
     cutoff = inputCutoff;
 }
 
+void AmoebaVdwForce::setCutoff(double inputCutoff) {
+    setCutoffDistance(inputCutoff);
+}
+
 double AmoebaVdwForce::getCutoff() const {
-    return cutoff;
+    return getCutoffDistance();
 }
 
 AmoebaVdwForce::NonbondedMethod AmoebaVdwForce::getNonbondedMethod() const {

plugins/amoeba/openmmapi/src/AmoebaVdwForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2016 Stanford University and the Authors.      *
  * Authors:                                                                   *
  * Contributors:                                                              *
  *                                                                            *
@@ -62,7 +62,7 @@ void AmoebaVdwForceImpl::initialize(ContextImpl& context) {
     if (owner.getNonbondedMethod() == AmoebaVdwForce::CutoffPeriodic) {
         Vec3 boxVectors[3];
         system.getDefaultPeriodicBoxVectors(boxVectors[0], boxVectors[1], boxVectors[2]);
-        double cutoff = owner.getCutoff();
+        double cutoff = owner.getCutoffDistance();
         if (cutoff > 0.5*boxVectors[0][0] || cutoff > 0.5*boxVectors[1][1] || cutoff > 0.5*boxVectors[2][2])
             throw OpenMMException("AmoebaVdwForce: The cutoff distance cannot be greater than half the periodic box size.");
     }   
@@ -103,7 +103,7 @@ double AmoebaVdwForceImpl::calcDispersionCorrection(const System& system, const
     }
 
     // Compute the VdW tapering coefficients.  Mostly copied from amoebaCudaGpu.cpp.
-    double cutoff = force.getCutoff();
+    double cutoff = force.getCutoffDistance();
     double vdwTaper = 0.90; // vdwTaper is a scaling factor, it is not a distance.
     double c0 = 0.0;
     double c1 = 0.0;

plugins/amoeba/platforms/cuda/src/AmoebaCudaKernels.cpp

@@ -1146,11 +1146,10 @@ void CudaCalcAmoebaMultipoleForceKernel::initialize(const System& system, const
         coefficients << cu.doubleToString(sum);
     }
     defines["EXTRAPOLATION_COEFFICIENTS_SUM"] = coefficients.str();
-    alpha = force.getAEwald();
     if (usePME) {
-        vector<int> pmeGridDimension;
-        force.getPmeGridDimensions(pmeGridDimension);
-        if (pmeGridDimension[0] == 0 || alpha == 0.0) {
+        int nx, ny, nz;
+        force.getPMEParameters(alpha, nx, ny, nz);
+        if (nx == 0 || alpha == 0.0) {
             NonbondedForce nb;
             nb.setEwaldErrorTolerance(force.getEwaldErrorTolerance());
             nb.setCutoffDistance(force.getCutoffDistance());
@@ -1159,9 +1158,9 @@ void CudaCalcAmoebaMultipoleForceKernel::initialize(const System& system, const
             gridSizeY = CudaFFT3D::findLegalDimension(gridSizeY);
             gridSizeZ = CudaFFT3D::findLegalDimension(gridSizeZ);
         } else {
-            gridSizeX = CudaFFT3D::findLegalDimension(pmeGridDimension[0]);
-            gridSizeY = CudaFFT3D::findLegalDimension(pmeGridDimension[1]);
-            gridSizeZ = CudaFFT3D::findLegalDimension(pmeGridDimension[2]);
+            gridSizeX = CudaFFT3D::findLegalDimension(nx);
+            gridSizeY = CudaFFT3D::findLegalDimension(ny);
+            gridSizeZ = CudaFFT3D::findLegalDimension(nz);
         }
         defines["EWALD_ALPHA"] = cu.doubleToString(alpha);
         defines["SQRT_PI"] = cu.doubleToString(sqrt(M_PI));
@@ -1993,6 +1992,27 @@ void CudaCalcAmoebaMultipoleForceKernel::ensureMultipolesValid(ContextImpl& cont
         context.calcForcesAndEnergy(false, false, -1);
 }
 
+
+void CudaCalcAmoebaMultipoleForceKernel::getLabFramePermanentDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
+    ensureMultipolesValid(context);
+    int numParticles = cu.getNumAtoms();
+    dipoles.resize(numParticles);
+    const vector<int>& order = cu.getAtomIndex();
+    if (cu.getUseDoublePrecision()) {
+        vector<double> labDipoleVec;
+        labFrameDipoles->download(labDipoleVec);
+        for (int i = 0; i < numParticles; i++)
+            dipoles[order[i]] = Vec3(labDipoleVec[3*i], labDipoleVec[3*i+1], labDipoleVec[3*i+2]);
+    }
+    else {
+        vector<float> labDipoleVec;
+        labFrameDipoles->download(labDipoleVec);
+        for (int i = 0; i < numParticles; i++)
+            dipoles[order[i]] = Vec3(labDipoleVec[3*i], labDipoleVec[3*i+1], labDipoleVec[3*i+2]);
+    }
+}
+
+
 void CudaCalcAmoebaMultipoleForceKernel::getInducedDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
     ensureMultipolesValid(context);
     int numParticles = cu.getNumAtoms();
@@ -2012,6 +2032,48 @@ void CudaCalcAmoebaMultipoleForceKernel::getInducedDipoles(ContextImpl& context,
     }
 }
 
+
+void CudaCalcAmoebaMultipoleForceKernel::getTotalDipoles(ContextImpl& context, vector<Vec3>& dipoles) {
+    ensureMultipolesValid(context);
+    int numParticles = cu.getNumAtoms();
+    dipoles.resize(numParticles);
+    const vector<int>& order = cu.getAtomIndex();
+    if (cu.getUseDoublePrecision()) {
+        vector<double4> posqVec;
+        vector<double> labDipoleVec;
+        vector<double> inducedDipoleVec;
+        double totalDipoleVecX;
+        double totalDipoleVecY;
+        double totalDipoleVecZ;
+        inducedDipole->download(inducedDipoleVec);
+        labFrameDipoles->download(labDipoleVec);
+        cu.getPosq().download(posqVec);
+        for (int i = 0; i < numParticles; i++) {
+            totalDipoleVecX = labDipoleVec[3*i] + inducedDipoleVec[3*i];
+            totalDipoleVecY = labDipoleVec[3*i+1] + inducedDipoleVec[3*i+1];
+            totalDipoleVecZ = labDipoleVec[3*i+2] + inducedDipoleVec[3*i+2];
+            dipoles[order[i]] = Vec3(totalDipoleVecX, totalDipoleVecY, totalDipoleVecZ);
+        }
+    }
+    else {
+        vector<float4> posqVec;
+        vector<float> labDipoleVec;
+        vector<float> inducedDipoleVec;
+        float totalDipoleVecX;
+        float totalDipoleVecY;
+        float totalDipoleVecZ;
+        inducedDipole->download(inducedDipoleVec);
+        labFrameDipoles->download(labDipoleVec);
+        cu.getPosq().download(posqVec);
+        for (int i = 0; i < numParticles; i++) {
+            totalDipoleVecX = labDipoleVec[3*i] + inducedDipoleVec[3*i];
+            totalDipoleVecY = labDipoleVec[3*i+1] + inducedDipoleVec[3*i+1];
+            totalDipoleVecZ = labDipoleVec[3*i+2] + inducedDipoleVec[3*i+2];
+            dipoles[order[i]] = Vec3(totalDipoleVecX, totalDipoleVecY, totalDipoleVecZ);
+        }
+    }
+}
+
 void CudaCalcAmoebaMultipoleForceKernel::getElectrostaticPotential(ContextImpl& context, const vector<Vec3>& inputGrid, vector<double>& outputElectrostaticPotential) {
     ensureMultipolesValid(context);
     int numPoints = inputGrid.size();
@@ -2165,6 +2227,7 @@ void CudaCalcAmoebaMultipoleForceKernel::computeSystemMultipoleMoments(ContextIm
     outputMultipoleMoments[12] = 100.0*zzqdp*debye;
 }
 
+
 void CudaCalcAmoebaMultipoleForceKernel::getSystemMultipoleMoments(ContextImpl& context, vector<double>& outputMultipoleMoments) {
     ensureMultipolesValid(context);
     if (cu.getUseDoublePrecision())
@@ -2601,15 +2664,15 @@ void CudaCalcAmoebaVdwForceKernel::initialize(const System& system, const Amoeba
         replacements["EPSILON_COMBINING_RULE"] = "4";
     else
         throw OpenMMException("Illegal combining rule for sigma: "+sigmaCombiningRule);
-    double cutoff = force.getCutoff();
+    double cutoff = force.getCutoffDistance();
     double taperCutoff = cutoff*0.9;
-    replacements["CUTOFF_DISTANCE"] = cu.doubleToString(force.getCutoff());
+    replacements["CUTOFF_DISTANCE"] = cu.doubleToString(force.getCutoffDistance());
     replacements["TAPER_CUTOFF"] = cu.doubleToString(taperCutoff);
     replacements["TAPER_C3"] = cu.doubleToString(10/pow(taperCutoff-cutoff, 3.0));
     replacements["TAPER_C4"] = cu.doubleToString(15/pow(taperCutoff-cutoff, 4.0));
     replacements["TAPER_C5"] = cu.doubleToString(6/pow(taperCutoff-cutoff, 5.0));
     bool useCutoff = (force.getNonbondedMethod() != AmoebaVdwForce::NoCutoff);
-    nonbonded->addInteraction(useCutoff, useCutoff, true, force.getCutoff(), exclusions,
+    nonbonded->addInteraction(useCutoff, useCutoff, true, force.getCutoffDistance(), exclusions,
         cu.replaceStrings(CudaAmoebaKernelSources::amoebaVdwForce2, replacements), 0);
     
     // Create the other kernels.

plugins/amoeba/platforms/cuda/src/AmoebaCudaKernels.h

@@ -328,6 +328,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+     /**
+     * Get the LabFrame dipole moments of all particles.
+     * 
+     * @param context    the Context for which to get the induced dipoles
+     * @param dipoles    the induced dipole moment of particle i is stored into the i'th element
+     */
+    void getLabFramePermanentDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
     /**
      * Get the induced dipole moments of all particles.
      * 
@@ -335,6 +342,13 @@ public:
      * @param dipoles    the induced dipole moment of particle i is stored into the i'th element
      */
     void getInducedDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
+    /**
+     * Get the total dipole moments of all particles.
+     * 
+     * @param context    the Context for which to get the induced dipoles
+     * @param dipoles    the induced dipole moment of particle i is stored into the i'th element
+     */
+    void getTotalDipoles(ContextImpl& context, std::vector<Vec3>& dipoles);
     /**
      * Execute the kernel to calculate the electrostatic potential
      *

plugins/amoeba/platforms/cuda/src/kernels/multipoleElectrostatics.cu

@@ -488,6 +488,8 @@ extern "C" __global__ void computeElectrostatics(
 
 #ifdef USE_CUTOFF
     const unsigned int numTiles = interactionCount[0];
+    if (numTiles > maxTiles)
+        return; // There wasn't enough memory for the neighbor list.
     int pos = (int) (numTiles > maxTiles ? startTileIndex+warp*(long long)numTileIndices/totalWarps : warp*(long long)numTiles/totalWarps);
     int end = (int) (numTiles > maxTiles ? startTileIndex+(warp+1)*(long long)numTileIndices/totalWarps : (warp+1)*(long long)numTiles/totalWarps);
 #else
@@ -508,34 +510,31 @@ extern "C" __global__ void computeElectrostatics(
         
         int x, y;
 #ifdef USE_CUTOFF
-        if (numTiles <= maxTiles)
-            x = tiles[pos];
-        else
-#endif
-        {
-            y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = tiles[pos];
+#else
+        y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+        if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
+            y += (x < y ? -1 : 1);
             x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
-                y += (x < y ? -1 : 1);
-                x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            }
+        }
 
-            // Skip over tiles that have exclusions, since they were already processed.
+        // Skip over tiles that have exclusions, since they were already processed.
 
-            while (skipTiles[tbx+TILE_SIZE-1] < pos) {
-                if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
-                    ushort2 tile = exclusionTiles[skipBase+tgx];
-                    skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
-                }
-                else
-                    skipTiles[threadIdx.x] = end;
-                skipBase += TILE_SIZE;            
-                currentSkipIndex = tbx;
+        while (skipTiles[tbx+TILE_SIZE-1] < pos) {
+            if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
+                ushort2 tile = exclusionTiles[skipBase+tgx];
+                skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
             }
-            while (skipTiles[currentSkipIndex] < pos)
-                currentSkipIndex++;
-            includeTile = (skipTiles[currentSkipIndex] != pos);
+            else
+                skipTiles[threadIdx.x] = end;
+            skipBase += TILE_SIZE;            
+            currentSkipIndex = tbx;
         }
+        while (skipTiles[currentSkipIndex] < pos)
+            currentSkipIndex++;
+        includeTile = (skipTiles[currentSkipIndex] != pos);
+#endif
         if (includeTile) {
             unsigned int atom1 = x*TILE_SIZE + tgx;
 

plugins/amoeba/platforms/cuda/src/kernels/multipoleFixedField.cu

@@ -592,6 +592,8 @@ extern "C" __global__ void computeFixedField(
 
 #ifdef USE_CUTOFF
     const unsigned int numTiles = interactionCount[0];
+    if (numTiles > maxTiles)
+        return; // There wasn't enough memory for the neighbor list.
     int pos = (int) (numTiles > maxTiles ? startTileIndex+warp*(long long)numTileIndices/totalWarps : warp*(long long)numTiles/totalWarps);
     int end = (int) (numTiles > maxTiles ? startTileIndex+(warp+1)*(long long)numTileIndices/totalWarps : (warp+1)*(long long)numTiles/totalWarps);
 #else
@@ -612,34 +614,31 @@ extern "C" __global__ void computeFixedField(
         
         int x, y;
 #ifdef USE_CUTOFF
-        if (numTiles <= maxTiles)
-            x = tiles[pos];
-        else
-#endif
-        {
-            y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = tiles[pos];
+#else
+        y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+        if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
+            y += (x < y ? -1 : 1);
             x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
-                y += (x < y ? -1 : 1);
-                x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            }
+        }
 
-            // Skip over tiles that have exclusions, since they were already processed.
+        // Skip over tiles that have exclusions, since they were already processed.
 
-            while (skipTiles[tbx+TILE_SIZE-1] < pos) {
-                if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
-                    ushort2 tile = exclusionTiles[skipBase+tgx];
-                    skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
-                }
-                else
-                    skipTiles[threadIdx.x] = end;
-                skipBase += TILE_SIZE;            
-                currentSkipIndex = tbx;
+        while (skipTiles[tbx+TILE_SIZE-1] < pos) {
+            if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
+                ushort2 tile = exclusionTiles[skipBase+tgx];
+                skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
             }
-            while (skipTiles[currentSkipIndex] < pos)
-                currentSkipIndex++;
-            includeTile = (skipTiles[currentSkipIndex] != pos);
+            else
+                skipTiles[threadIdx.x] = end;
+            skipBase += TILE_SIZE;            
+            currentSkipIndex = tbx;
         }
+        while (skipTiles[currentSkipIndex] < pos)
+            currentSkipIndex++;
+        includeTile = (skipTiles[currentSkipIndex] != pos);
+#endif
         if (includeTile) {
             unsigned int atom1 = x*TILE_SIZE + tgx;
 

plugins/amoeba/platforms/cuda/src/kernels/multipoleInducedField.cu

@@ -454,6 +454,8 @@ extern "C" __global__ void computeInducedField(
 
 #ifdef USE_CUTOFF
     const unsigned int numTiles = interactionCount[0];
+    if (numTiles > maxTiles)
+        return; // There wasn't enough memory for the neighbor list.
     int pos = (int) (numTiles > maxTiles ? startTileIndex+warp*(long long)numTileIndices/totalWarps : warp*(long long)numTiles/totalWarps);
     int end = (int) (numTiles > maxTiles ? startTileIndex+(warp+1)*(long long)numTileIndices/totalWarps : (warp+1)*(long long)numTiles/totalWarps);
 #else
@@ -474,34 +476,31 @@ extern "C" __global__ void computeInducedField(
         
         int x, y;
 #ifdef USE_CUTOFF
-        if (numTiles <= maxTiles)
-            x = tiles[pos];
-        else
-#endif
-        {
-            y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = tiles[pos];
+#else
+        y = (int) floor(NUM_BLOCKS+0.5f-SQRT((NUM_BLOCKS+0.5f)*(NUM_BLOCKS+0.5f)-2*pos));
+        x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
+        if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
+            y += (x < y ? -1 : 1);
             x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            if (x < y || x >= NUM_BLOCKS) { // Occasionally happens due to roundoff error.
-                y += (x < y ? -1 : 1);
-                x = (pos-y*NUM_BLOCKS+y*(y+1)/2);
-            }
+        }
 
-            // Skip over tiles that have exclusions, since they were already processed.
+        // Skip over tiles that have exclusions, since they were already processed.
 
-            while (skipTiles[tbx+TILE_SIZE-1] < pos) {
-                if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
-                    ushort2 tile = exclusionTiles[skipBase+tgx];
-                    skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
-                }
-                else
-                    skipTiles[threadIdx.x] = end;
-                skipBase += TILE_SIZE;            
-                currentSkipIndex = tbx;
+        while (skipTiles[tbx+TILE_SIZE-1] < pos) {
+            if (skipBase+tgx < NUM_TILES_WITH_EXCLUSIONS) {
+                ushort2 tile = exclusionTiles[skipBase+tgx];
+                skipTiles[threadIdx.x] = tile.x + tile.y*NUM_BLOCKS - tile.y*(tile.y+1)/2;
             }
-            while (skipTiles[currentSkipIndex] < pos)
-                currentSkipIndex++;
-            includeTile = (skipTiles[currentSkipIndex] != pos);
+            else
+                skipTiles[threadIdx.x] = end;
+            skipBase += TILE_SIZE;            
+            currentSkipIndex = tbx;
         }
+        while (skipTiles[currentSkipIndex] < pos)
+            currentSkipIndex++;
+        includeTile = (skipTiles[currentSkipIndex] != pos);
+#endif
         if (includeTile) {
             unsigned int atom1 = x*TILE_SIZE + tgx;