TestCudaCustomBondForce.cpp

/* -------------------------------------------------------------------------- *
 *                                   OpenMM                                   *
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 * 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.               *
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 * Authors: Peter Eastman                                                     *
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/**
 * This tests the CUDA implementation of CustomBondForce.
 */

#include "openmm/internal/AssertionUtilities.h"
#include "openmm/Context.h"
#include "CudaPlatform.h"
#include "openmm/CustomBondForce.h"
#include "openmm/System.h"
#include "openmm/VerletIntegrator.h"
#include "../src/SimTKUtilities/SimTKOpenMMRealType.h"
#include <iostream>
#include <vector>

using namespace OpenMM;
using namespace std;

const double TOL = 1e-5;

CudaPlatform platform;

void testBonds() {
    System system;
    system.addParticle(1.0);
    system.addParticle(1.0);
    system.addParticle(1.0);
    VerletIntegrator integrator(0.01);
    CustomBondForce* forceField = new CustomBondForce("scale*k*(r-r0)^2");
    forceField->addPerBondParameter("r0");
    forceField->addPerBondParameter("k");
    forceField->addGlobalParameter("scale", 0.5);
    vector<double> parameters(2);
    parameters[0] = 1.5;
    parameters[1] = 0.8;
    forceField->addBond(0, 1, parameters);
    parameters[0] = 1.2;
    parameters[1] = 0.7;
    forceField->addBond(1, 2, parameters);
    system.addForce(forceField);
    Context context(system, integrator, platform);
    vector<Vec3> positions(3);
    positions[0] = Vec3(0, 2, 0);
    positions[1] = Vec3(0, 0, 0);
    positions[2] = Vec3(1, 0, 0);
    context.setPositions(positions);
    State state = context.getState(State::Forces | State::Energy);
    {
        const vector<Vec3>& forces = state.getForces();
        ASSERT_EQUAL_VEC(Vec3(0, -0.8*0.5, 0), forces[0], TOL);
        ASSERT_EQUAL_VEC(Vec3(0.7*0.2, 0, 0), forces[2], TOL);
        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
        ASSERT_EQUAL_TOL(0.5*0.8*0.5*0.5 + 0.5*0.7*0.2*0.2, state.getPotentialEnergy(), TOL);
    }
    
    // Try changing the bond parameters and make sure it's still correct.
    
    parameters[0] = 1.6;
    parameters[1] = 0.9;
    forceField->setBondParameters(0, 0, 1, parameters);
    parameters[0] = 1.3;
    parameters[1] = 0.8;
    forceField->setBondParameters(1, 1, 2, parameters);
    forceField->updateParametersInContext(context);
    state = context.getState(State::Forces | State::Energy);
    {
        const vector<Vec3>& forces = state.getForces();
        ASSERT_EQUAL_VEC(Vec3(0, -0.9*0.4, 0), forces[0], TOL);
        ASSERT_EQUAL_VEC(Vec3(0.8*0.3, 0, 0), forces[2], TOL);
        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
        ASSERT_EQUAL_TOL(0.5*0.9*0.4*0.4 + 0.5*0.8*0.3*0.3, state.getPotentialEnergy(), TOL);
    }
}

void testManyParameters() {
    System system;
    system.addParticle(1.0);
    system.addParticle(1.0);
    VerletIntegrator integrator(0.01);
    CustomBondForce* forceField = new CustomBondForce("(a+b+c+d+e+f+g+h+i)*r");
    forceField->addPerBondParameter("a");
    forceField->addPerBondParameter("b");
    forceField->addPerBondParameter("c");
    forceField->addPerBondParameter("d");
    forceField->addPerBondParameter("e");
    forceField->addPerBondParameter("f");
    forceField->addPerBondParameter("g");
    forceField->addPerBondParameter("h");
    forceField->addPerBondParameter("i");
    vector<double> parameters(forceField->getNumPerBondParameters());
    for (int i = 0; i < parameters.size(); i++)
        parameters[i] = i;
    forceField->addBond(0, 1, parameters);
    system.addForce(forceField);
    Context context(system, integrator, platform);
    vector<Vec3> positions(2);
    positions[0] = Vec3(0, 0, 0);
    positions[1] = Vec3(0, 2.5, 0);
    context.setPositions(positions);
    State state = context.getState(State::Forces | State::Energy);
    const vector<Vec3>& forces = state.getForces();
    double f = 1+2+3+4+5+6+7+8;
    ASSERT_EQUAL_VEC(Vec3(0, f, 0), forces[0], TOL);
    ASSERT_EQUAL_VEC(Vec3(0, -f, 0), forces[1], TOL);
    ASSERT_EQUAL_TOL(f*2.5, state.getPotentialEnergy(), TOL);
}

void testParallelComputation() {
    System system;
    const int numParticles = 200;
    for (int i = 0; i < numParticles; i++)
        system.addParticle(1.0);
    CustomBondForce* force = new CustomBondForce(("(r-1.1)^2"));
    vector<double> params;
    for (int i = 1; i < numParticles; i++)
        force->addBond(i-1, i, params);
    system.addForce(force);
    vector<Vec3> positions(numParticles);
    for (int i = 0; i < numParticles; i++)
        positions[i] = Vec3(i, 0, 0);
    VerletIntegrator integrator1(0.01);
    Context context1(system, integrator1, platform);
    context1.setPositions(positions);
    State state1 = context1.getState(State::Forces | State::Energy);
    VerletIntegrator integrator2(0.01);
    string deviceIndex = platform.getPropertyValue(context1, CudaPlatform::CudaDeviceIndex());
    map<string, string> props;
    props[CudaPlatform::CudaDeviceIndex()] = deviceIndex+","+deviceIndex;
    Context context2(system, integrator2, platform, props);
    context2.setPositions(positions);
    State state2 = context2.getState(State::Forces | State::Energy);
    ASSERT_EQUAL_TOL(state1.getPotentialEnergy(), state2.getPotentialEnergy(), 1e-5);
    for (int i = 0; i < numParticles; i++)
        ASSERT_EQUAL_VEC(state1.getForces()[i], state2.getForces()[i], 1e-5);
}

int main(int argc, char* argv[]) {
    try {
        if (argc > 1)
            platform.setPropertyDefaultValue("CudaPrecision", string(argv[1]));
        testBonds();
        testManyParameters();
        testParallelComputation();
    }
    catch(const exception& e) {
        cout << "exception: " << e.what() << endl;
        return 1;
    }
    cout << "Done" << endl;
    return 0;
}