LangevinIntegrator.cpp

/* -------------------------------------------------------------------------- *
 *                                   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) 2008 Stanford University and the Authors.           *
 * Authors: Peter Eastman                                                     *
 * Contributors:                                                              *
 *                                                                            *
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 * Software is furnished to do so, subject to the following conditions:       *
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 * The above copyright notice and this permission notice shall be included in *
 * all copies or substantial portions of the Software.                        *
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#include "LangevinIntegrator.h"
#include "OpenMMContext.h"
#include "internal/OpenMMContextImpl.h"
#include "kernels.h"
#include <string>

using namespace OpenMM;
using std::string;
using std::vector;

LangevinIntegrator::LangevinIntegrator(double temperature, double frictionCoeff, double stepSize) {
    setTemperature(temperature);
    setFriction(frictionCoeff);
    setStepSize(stepSize);
    setConstraintTolerance(1e-4);
}

void LangevinIntegrator::initialize(OpenMMContextImpl& contextRef) {
    context = &contextRef;
    kernel = context->getPlatform().createKernel(IntegrateLangevinStepKernel::Name(), contextRef);
    dynamic_cast<IntegrateLangevinStepKernel&>(kernel.getImpl()).initialize(contextRef.getSystem(), *this);
}

vector<string> LangevinIntegrator::getKernelNames() {
    std::vector<std::string> names;
    names.push_back(IntegrateLangevinStepKernel::Name());
    return names;
}

void LangevinIntegrator::step(int steps) {
    for (int i = 0; i < steps; ++i) {
        context->updateContextState();
        context->calcForces();
        dynamic_cast<IntegrateLangevinStepKernel&>(kernel.getImpl()).execute(*context, *this);
        context->setTime(context->getTime()+getStepSize());
    }
}