#ifndef OPENMM_DRUDEFORCE_H_ #define OPENMM_DRUDEFORCE_H_ /* -------------------------------------------------------------------------- * * OpenMM * * -------------------------------------------------------------------------- * * This is part of the OpenMM molecular simulation toolkit originating from * * Simbios, the NIH National Center for Physics-Based Simulation of * * Biological Structures at Stanford, funded under the NIH Roadmap for * * Medical Research, grant U54 GM072970. See https://simtk.org. * * * * Portions copyright (c) 2013 Stanford University and the Authors. * * Authors: Peter Eastman * * Contributors: * * * * Permission is hereby granted, free of charge, to any person obtaining a * * copy of this software and associated documentation files (the "Software"), * * to deal in the Software without restriction, including without limitation * * the rights to use, copy, modify, merge, publish, distribute, sublicense, * * and/or sell copies of the Software, and to permit persons to whom the * * Software is furnished to do so, subject to the following conditions: * * * * The above copyright notice and this permission notice shall be included in * * all copies or substantial portions of the Software. * * * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * * THE AUTHORS, CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE * * USE OR OTHER DEALINGS IN THE SOFTWARE. * * -------------------------------------------------------------------------- */ #include "openmm/Context.h" #include "openmm/Force.h" #include #include "internal/windowsExportDrude.h" namespace OpenMM { /** * This class implements forces that are specific to Drude oscillators. There are two distinct forces * it applies: an anisotropic harmonic force connecting each Drude particle to its parent particle; and * a screened Coulomb interaction between specific pairs of dipoles. The latter is typically used between * closely bonded particles whose Coulomb interaction would otherwise be fully excluded. * * To use this class, create a DrudeForce object, then call addParticle() once for each Drude particle in the * System to define its parameters. After a particle has been added, you can modify its force field parameters * by calling setParticleParameters(). This will have no effect on Contexts that already exist unless you * call updateParametersInContext(). Likewise, call addScreenedPair() for each pair of dipoles (each dipole * consisting of a Drude particle and its parent) that should be computed. */ class OPENMM_EXPORT_DRUDE DrudeForce : public Force { public: /** * Create a DrudeForce. */ DrudeForce(); /** * Get the number of particles for which force field parameters have been defined. */ int getNumParticles() const { return particles.size(); } /** * Get the number of special interactions that should be calculated differently from other interactions. */ int getNumScreenedPairs() const { return screenedPairs.size(); } /** * Add a Drude particle to which forces should be applied. * * @param particle the index within the System of the Drude particle * @param particle1 the index within the System of the particle to which the Drude particle is attached * @param particle2 the index within the System of the second particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso12 will be ignored. * @param particle3 the index within the System of the third particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param particle4 the index within the System of the fourth particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param charge The charge on the Drude particle * @param polarizability The isotropic polarizability * @param aniso12 The scale factor for the polarizability along the direction defined by particle1 and particle2 * @param aniso34 The scale factor for the polarizability along the direction defined by particle3 and particle4 * @return the index of the particle that was added */ int addParticle(int particle, int particle1, int particle2, int particle3, int particle4, double charge, double polarizability, double aniso12, double aniso34); /** * Get the parameters for a Drude particle. * * @param index the index of the Drude particle for which to get parameters * @param[out] particle the index within the System of the Drude particle * @param[out] particle1 the index within the System of the particle to which the Drude particle is attached * @param[out] particle2 the index within the System of the second particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso12 will be ignored. * @param[out] particle3 the index within the System of the third particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param[out] particle4 the index within the System of the fourth particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param[out] charge The charge on the Drude particle * @param[out] polarizability The isotropic polarizability * @param[out] aniso12 The scale factor for the polarizability along the direction defined by particle1 and particle2 * @param[out] aniso34 The scale factor for the polarizability along the direction defined by particle3 and particle4 */ void getParticleParameters(int index, int& particle, int& particle1, int& particle2, int& particle3, int& particle4, double& charge, double& polarizability, double& aniso12, double& aniso34) const; /** * Set the parameters for a Drude particle. * * @param index the index of the Drude particle for which to set parameters * @param particle the index within the System of the Drude particle * @param particle1 the index within the System of the particle to which the Drude particle is attached * @param particle2 the index within the System of the second particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso12 will be ignored. * @param particle3 the index within the System of the third particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param particle4 the index within the System of the fourth particle used for defining anisotropic polarizability. * This may be set to -1, in which case aniso34 will be ignored. * @param charge The charge on the Drude particle * @param polarizability The isotropic polarizability * @param aniso12 The scale factor for the polarizability along the direction defined by particle1 and particle2 * @param aniso34 The scale factor for the polarizability along the direction defined by particle3 and particle4 */ void setParticleParameters(int index, int particle, int particle1, int particle2, int particle3, int particle4, double charge, double polarizability, double aniso12, double aniso34); /** * Add an interaction to the list of screened pairs. * * @param particle1 the index within this Force of the first particle involved in the interaction * @param particle2 the index within this Force of the second particle involved in the interaction * @param thole the Thole screening factor * @return the index of the screenedPair that was added */ int addScreenedPair(int particle1, int particle2, double thole); /** * Get the force field parameters for screened pair. * * @param index the index of the pair for which to get parameters * @param[out] particle1 the index within this Force of the first particle involved in the interaction * @param[out] particle2 the index within this Force of the second particle involved in the interaction * @param[out] thole the Thole screening factor */ void getScreenedPairParameters(int index, int& particle1, int& particle2, double& thole) const; /** * Set the force field parameters for screened pair. * * @param index the index of the pair for which to get parameters * @param particle1 the index within this Force of the first particle involved in the interaction * @param particle2 the index within this Force of the second particle involved in the interaction * @param thole the Thole screening factor */ void setScreenedPairParameters(int index, int particle1, int particle2, double thole); /** * Update the particle and screened pair parameters in a Context to match those stored in this Force object. This method * provides an efficient method to update certain parameters in an existing Context without needing to reinitialize it. * Simply call setParticleParameters() and setScreenedPairParameters() to modify this object's parameters, then call * updateParametersInContext() to copy them over to the Context. * * This method has several limitations. It can be used to modify the numeric parameters associated with a particle or * screened pair (polarizability, thole, etc.), but not the identities of the particles they involve. It also cannot * be used to add new particles or screenedPairs, only to change the parameters of existing ones. */ void updateParametersInContext(Context& context); /** * Returns whether or not this force makes use of periodic boundary * conditions. * * @returns true if nonbondedMethod uses PBC and false otherwise */ bool usesPeriodicBoundaryConditions() const { return false; } protected: ForceImpl* createImpl() const; private: class ParticleInfo; class ScreenedPairInfo; std::vector particles; std::vector screenedPairs; }; /** * This is an internal class used to record information about a particle. * @private */ class DrudeForce::ParticleInfo { public: int particle, particle1, particle2, particle3, particle4; double charge, polarizability, aniso12, aniso34; ParticleInfo() { particle = particle1 = particle2 = particle3 = particle4 = -1; charge = polarizability = aniso12 = aniso34 = 0.0; } ParticleInfo(int particle, int particle1, int particle2, int particle3, int particle4, double charge, double polarizability, double aniso12, double aniso34) : particle(particle), particle1(particle1), particle2(particle2), particle3(particle3), particle4(particle4), charge(charge), polarizability(polarizability), aniso12(aniso12), aniso34(aniso34) { } }; /** * This is an internal class used to record information about a screenedPair. * @private */ class DrudeForce::ScreenedPairInfo { public: int particle1, particle2; double thole; ScreenedPairInfo() { particle1 = particle2 = -1; thole = 0.0; } ScreenedPairInfo(int particle1, int particle2, double thole) : particle1(particle1), particle2(particle2), thole(thole) { } }; } // namespace OpenMM #endif /*OPENMM_DRUDEFORCE_H_*/