void testPMEParameters() {
// Create a cloud of random point charges.
const int numParticles = 51;
const double boxWidth = 4.7;
System system;
system.setDefaultPeriodicBoxVectors(Vec3(boxWidth, 0, 0), Vec3(0, boxWidth, 0), Vec3(0, 0, boxWidth));
NonbondedForce* force = new NonbondedForce();
system.addForce(force);
vector<Vec3> positions(numParticles);
OpenMM_SFMT::SFMT sfmt;
init_gen_rand(0, sfmt);
for (int i = 0; i < numParticles; i++) {
system.addParticle(1.0);
force->addParticle(-1.0+i*2.0/(numParticles-1), 1.0, 0.0);
positions[i] = Vec3(boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt));
}
force->setNonbondedMethod(NonbondedForce::PME);
ReferencePlatform platform;
// Compute the energy with an error tolerance of 1e-3.
force->setEwaldErrorTolerance(1e-3);
VerletIntegrator integrator1(0.01);
Context context1(system, integrator1, platform);
context1.setPositions(positions);
double energy1 = context1.getState(State::Energy).getPotentialEnergy();
// Try again with an error tolerance of 1e-4.
force->setEwaldErrorTolerance(1e-4);
VerletIntegrator integrator2(0.01);
Context context2(system, integrator2, platform);
context2.setPositions(positions);
double energy2 = context2.getState(State::Energy).getPotentialEnergy();
// Now explicitly set the parameters. These should match the values that were
// used for tolerance 1e-3.
force->setPMEParameters(2.49291157051793, 32, 32, 32);
VerletIntegrator integrator3(0.01);
Context context3(system, integrator3, platform);
context3.setPositions(positions);
double energy3 = context3.getState(State::Energy).getPotentialEnergy();
ASSERT_EQUAL_TOL(energy1, energy3, 1e-6);
ASSERT(fabs((energy1-energy2)/energy1) > 1e-5);
}
void testEwald2Ions() {
System system;
system.addParticle(1.0);
system.addParticle(1.0);
VerletIntegrator integrator(0.01);
NonbondedForce* nonbonded = new NonbondedForce();
nonbonded->addParticle(1.0, 1, 0);
nonbonded->addParticle(-1.0, 1, 0);
nonbonded->setNonbondedMethod(NonbondedForce::Ewald);
const double cutoff = 2.0;
nonbonded->setCutoffDistance(cutoff);
nonbonded->setEwaldErrorTolerance(TOL);
system.setDefaultPeriodicBoxVectors(Vec3(6, 0, 0), Vec3(0, 6, 0), Vec3(0, 0, 6));
system.addForce(nonbonded);
Context context(system, integrator, platform);
vector<Vec3> positions(2);
positions[0] = Vec3(3.048000,2.764000,3.156000);
positions[1] = Vec3(2.809000,2.888000,2.571000);
context.setPositions(positions);
State state = context.getState(State::Forces | State::Energy);
const vector<Vec3>& forces = state.getForces();
ASSERT_EQUAL_VEC(Vec3(-123.711, 64.1877, -302.716), forces[0], 10*TOL);
ASSERT_EQUAL_VEC(Vec3( 123.711, -64.1877, 302.716), forces[1], 10*TOL);
ASSERT_EQUAL_TOL(-217.276, state.getPotentialEnergy(), 0.01/*10*TOL*/);
}
void testForceEnergyConsistency() {
// Create a box of polarizable particles.
const int gridSize = 3;
const int numAtoms = gridSize*gridSize*gridSize;
const double spacing = 0.6;
const double boxSize = spacing*(gridSize+1);
const double temperature = 300.0;
const double temperatureDrude = 10.0;
System system;
vector<Vec3> positions;
NonbondedForce* nonbonded = new NonbondedForce();
DrudeForce* drude = new DrudeForce();
system.addForce(nonbonded);
system.addForce(drude);
system.setDefaultPeriodicBoxVectors(Vec3(boxSize, 0, 0), Vec3(0, boxSize, 0), Vec3(0, 0, boxSize));
nonbonded->setNonbondedMethod(NonbondedForce::PME);
nonbonded->setCutoffDistance(1.0);
nonbonded->setUseSwitchingFunction(true);
nonbonded->setSwitchingDistance(0.9);
nonbonded->setEwaldErrorTolerance(5e-5);
for (int i = 0; i < numAtoms; i++) {
int startIndex = system.getNumParticles();
system.addParticle(1.0);
system.addParticle(1.0);
nonbonded->addParticle(1.0, 0.3, 1.0);
nonbonded->addParticle(-1.0, 0.3, 1.0);
nonbonded->addException(startIndex, startIndex+1, 0, 1, 0);
drude->addParticle(startIndex+1, startIndex, -1, -1, -1, -1.0, 0.001, 1, 1);
}
for (int i = 0; i < gridSize; i++)
for (int j = 0; j < gridSize; j++)
for (int k = 0; k < gridSize; k++) {
Vec3 pos(i*spacing, j*spacing, k*spacing);
positions.push_back(pos);
positions.push_back(pos);
}
// Simulate it and check that force and energy remain consistent.
DrudeLangevinIntegrator integ(temperature, 50.0, temperatureDrude, 50.0, 0.001);
Platform& platform = Platform::getPlatformByName("Reference");
Context context(system, integ, platform);
context.setPositions(positions);
State prevState;
for (int i = 0; i < 100; i++) {
State state = context.getState(State::Energy | State::Forces | State::Positions);
if (i > 0) {
double expectedEnergyChange = 0;
for (int j = 0; j < system.getNumParticles(); j++) {
Vec3 delta = state.getPositions()[j]-prevState.getPositions()[j];
expectedEnergyChange -= 0.5*(state.getForces()[j]+prevState.getForces()[j]).dot(delta);
}
ASSERT_EQUAL_TOL(expectedEnergyChange, state.getPotentialEnergy()-prevState.getPotentialEnergy(), 0.05);
}
prevState = state;
integ.step(1);
}
}
void testWaterSystem() {
ReferencePlatform platform;
System system;
static int numParticles = 648;
const double boxSize = 1.86206;
for (int i = 0 ; i < numParticles ; i++)
{
system.addParticle(1.0);
}
VerletIntegrator integrator(0.01);
NonbondedForce* nonbonded = new NonbondedForce();
for (int i = 0 ; i < numParticles/3 ; i++)
{
nonbonded->addParticle(-0.82, 1, 0);
nonbonded->addParticle(0.41, 1, 0);
nonbonded->addParticle(0.41, 1, 0);
}
nonbonded->setNonbondedMethod(NonbondedForce::CutoffPeriodic);
const double cutoff = 0.8;
nonbonded->setCutoffDistance(cutoff);
system.setDefaultPeriodicBoxVectors(Vec3(boxSize, 0, 0), Vec3(0, boxSize, 0), Vec3(0, 0, boxSize));
nonbonded->setEwaldErrorTolerance(EWALD_TOL);
system.addForce(nonbonded);
Context context(system, integrator, platform);
vector<Vec3> positions(numParticles);
#include "water.dat"
context.setPositions(positions);
State state1 = context.getState(State::Forces | State::Energy);
const vector<Vec3>& forces = state1.getForces();
// Take a small step in the direction of the energy gradient.
double norm = 0.0;
for (int i = 0; i < numParticles; ++i) {
Vec3 f = state1.getForces()[i];
norm += f[0]*f[0] + f[1]*f[1] + f[2]*f[2];
}
norm = std::sqrt(norm);
const double delta = 1e-3;
double step = delta/norm;
for (int i = 0; i < numParticles; ++i) {
Vec3 p = positions[i];
Vec3 f = state1.getForces()[i];
positions[i] = Vec3(p[0]-f[0]*step, p[1]-f[1]*step, p[2]-f[2]*step);
}
context.setPositions(positions);
// See whether the potential energy changed by the expected amount.
nonbonded->setNonbondedMethod(NonbondedForce::Ewald);
State state2 = context.getState(State::Energy);
ASSERT_EQUAL_TOL(norm, (state2.getPotentialEnergy()-state1.getPotentialEnergy())/delta, 0.01)
}
void testSerialization() {
// Create a Force.
NonbondedForce force;
force.setNonbondedMethod(NonbondedForce::CutoffPeriodic);
force.setCutoffDistance(2.0);
force.setEwaldErrorTolerance(1e-3);
force.setReactionFieldDielectric(50.0);
force.setUseDispersionCorrection(false);
force.addParticle(1, 0.1, 0.01);
force.addParticle(0.5, 0.2, 0.02);
force.addParticle(-0.5, 0.3, 0.03);
force.addException(0, 1, 2, 0.5, 0.1);
force.addException(1, 2, 0.2, 0.4, 0.2);
// Serialize and then deserialize it.
stringstream buffer;
XmlSerializer::serialize<NonbondedForce>(&force, "Force", buffer);
NonbondedForce* copy = XmlSerializer::deserialize<NonbondedForce>(buffer);
// Compare the two forces to see if they are identical.
NonbondedForce& force2 = *copy;
ASSERT_EQUAL(force.getNonbondedMethod(), force2.getNonbondedMethod());
ASSERT_EQUAL(force.getCutoffDistance(), force2.getCutoffDistance());
ASSERT_EQUAL(force.getEwaldErrorTolerance(), force2.getEwaldErrorTolerance());
ASSERT_EQUAL(force.getReactionFieldDielectric(), force2.getReactionFieldDielectric());
ASSERT_EQUAL(force.getUseDispersionCorrection(), force2.getUseDispersionCorrection());
ASSERT_EQUAL(force.getNumParticles(), force2.getNumParticles());
for (int i = 0; i < force.getNumParticles(); i++) {
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getParticleParameters(i, charge1, sigma1, epsilon1);
force2.getParticleParameters(i, charge2, sigma2, epsilon2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
ASSERT_EQUAL(force.getNumExceptions(), force2.getNumExceptions());
for (int i = 0; i < force.getNumExceptions(); i++) {
int a1, a2, b1, b2;
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getExceptionParameters(i, a1, b1, charge1, sigma1, epsilon1);
force2.getExceptionParameters(i, a2, b2, charge2, sigma2, epsilon2);
ASSERT_EQUAL(a1, a2);
ASSERT_EQUAL(b1, b2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
}
void testErrorTolerance(NonbondedForce::NonbondedMethod method) {
// Create a cloud of random point charges.
const int numParticles = 51;
const double boxWidth = 5.0;
System system;
system.setDefaultPeriodicBoxVectors(Vec3(boxWidth, 0, 0), Vec3(0, boxWidth, 0), Vec3(0, 0, boxWidth));
NonbondedForce* force = new NonbondedForce();
system.addForce(force);
vector<Vec3> positions(numParticles);
OpenMM_SFMT::SFMT sfmt;
init_gen_rand(0, sfmt);
for (int i = 0; i < numParticles; i++) {
system.addParticle(1.0);
force->addParticle(-1.0+i*2.0/(numParticles-1), 1.0, 0.0);
positions[i] = Vec3(boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt));
}
force->setNonbondedMethod(method);
ReferencePlatform platform;
// For various values of the cutoff and error tolerance, see if the actual error is reasonable.
for (double cutoff = 1.0; cutoff < boxWidth/2; cutoff *= 1.2) {
force->setCutoffDistance(cutoff);
vector<Vec3> refForces;
double norm = 0.0;
for (double tol = 5e-5; tol < 1e-3; tol *= 2.0) {
force->setEwaldErrorTolerance(tol);
VerletIntegrator integrator(0.01);
Context context(system, integrator, platform);
context.setPositions(positions);
State state = context.getState(State::Forces);
if (refForces.size() == 0) {
refForces = state.getForces();
for (int i = 0; i < numParticles; i++)
norm += refForces[i].dot(refForces[i]);
norm = sqrt(norm);
}
else {
double diff = 0.0;
for (int i = 0; i < numParticles; i++) {
Vec3 delta = refForces[i]-state.getForces()[i];
diff += delta.dot(delta);
}
diff = sqrt(diff)/norm;
ASSERT(diff < 2*tol);
}
}
}
}
void testEwaldExact() {
// Use a NaCl crystal to compare the calculated and Madelung energies
const int numParticles = 1000;
const double cutoff = 1.0;
const double boxSize = 2.82;
ReferencePlatform platform;
System system;
for (int i = 0; i < numParticles/2; i++)
system.addParticle(22.99);
for (int i = 0; i < numParticles/2; i++)
system.addParticle(35.45);
VerletIntegrator integrator(0.01);
NonbondedForce* nonbonded = new NonbondedForce();
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(1.0, 1.0,0.0);
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(-1.0, 1.0,0.0);
nonbonded->setNonbondedMethod(NonbondedForce::Ewald);
nonbonded->setCutoffDistance(cutoff);
system.setDefaultPeriodicBoxVectors(Vec3(boxSize, 0, 0), Vec3(0, boxSize, 0), Vec3(0, 0, boxSize));
nonbonded->setEwaldErrorTolerance(EWALD_TOL);
system.addForce(nonbonded);
Context context(system, integrator, platform);
vector<Vec3> positions(numParticles);
#include "nacl_crystal.dat"
context.setPositions(positions);
State state = context.getState(State::Forces | State::Energy);
const vector<Vec3>& forces = state.getForces();
// The potential energy of an ion in a crystal is
// E = - (M*e^2/ 4*pi*epsilon0*a0),
// where
// M : Madelung constant (dimensionless, for FCC cells such as NaCl it is 1.7476)
// e : 1.6022 × 10−19 C
// 4*pi*epsilon0: 1.112 × 10−10 C²/(J m)
// a0 : 0.282 x 10-9 m (perfect cell)
//
// E is then the energy per pair of ions, so for our case
// E has to be divided by 2 (per ion), multiplied by N(avogadro), multiplied by number of particles, and divided by 1000 for kJ
double exactEnergy = - (1.7476 * 1.6022e-19 * 1.6022e-19 * 6.02214e+23 * numParticles) / (1.112e-10 * 0.282e-9 * 2 * 1000);
//cout << "exact\t\t: " << exactEnergy << endl;
//cout << "calc\t\t: " << state.getPotentialEnergy() << endl;
ASSERT_EQUAL_TOL(exactEnergy, state.getPotentialEnergy(), 100*EWALD_TOL);
}
void testEwaldPME(bool includeExceptions) {
// Use amorphous NaCl system for the tests
const int numParticles = 894;
const double cutoff = 1.2;
const double boxSize = 3.00646;
double tol = 1e-5;
ReferencePlatform reference;
System system;
NonbondedForce* nonbonded = new NonbondedForce();
nonbonded->setNonbondedMethod(NonbondedForce::Ewald);
nonbonded->setCutoffDistance(cutoff);
nonbonded->setEwaldErrorTolerance(tol);
for (int i = 0; i < numParticles/2; i++)
system.addParticle(22.99);
for (int i = 0; i < numParticles/2; i++)
system.addParticle(35.45);
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(1.0, 1.0,0.0);
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(-1.0, 1.0,0.0);
system.setDefaultPeriodicBoxVectors(Vec3(boxSize, 0, 0), Vec3(0, boxSize, 0), Vec3(0, 0, boxSize));
system.addForce(nonbonded);
vector<Vec3> positions(numParticles);
#include "nacl_amorph.dat"
if (includeExceptions) {
// Add some exclusions.
for (int i = 0; i < numParticles-1; i++) {
Vec3 delta = positions[i]-positions[i+1];
if (sqrt(delta.dot(delta)) < 0.5*cutoff)
nonbonded->addException(i, i+1, i%2 == 0 ? 0.0 : 0.5, 1.0, 0.0);
}
}
// (1) Check whether the Reference and CPU platforms agree when using Ewald Method
VerletIntegrator integrator1(0.01);
VerletIntegrator integrator2(0.01);
Context cpuContext(system, integrator1, platform);
Context referenceContext(system, integrator2, reference);
cpuContext.setPositions(positions);
referenceContext.setPositions(positions);
State cpuState = cpuContext.getState(State::Forces | State::Energy);
State referenceState = referenceContext.getState(State::Forces | State::Energy);
tol = 1e-2;
for (int i = 0; i < numParticles; i++) {
ASSERT_EQUAL_VEC(referenceState.getForces()[i], cpuState.getForces()[i], tol);
}
tol = 1e-5;
ASSERT_EQUAL_TOL(referenceState.getPotentialEnergy(), cpuState.getPotentialEnergy(), tol);
// (2) Check whether Ewald method in CPU is self-consistent
double norm = 0.0;
for (int i = 0; i < numParticles; ++i) {
Vec3 f = cpuState.getForces()[i];
norm += f[0]*f[0] + f[1]*f[1] + f[2]*f[2];
}
norm = std::sqrt(norm);
const double delta = 5e-3;
double step = delta/norm;
for (int i = 0; i < numParticles; ++i) {
Vec3 p = positions[i];
Vec3 f = cpuState.getForces()[i];
positions[i] = Vec3(p[0]-f[0]*step, p[1]-f[1]*step, p[2]-f[2]*step);
}
VerletIntegrator integrator3(0.01);
Context cpuContext2(system, integrator3, platform);
cpuContext2.setPositions(positions);
tol = 1e-2;
State cpuState2 = cpuContext2.getState(State::Energy);
ASSERT_EQUAL_TOL(norm, (cpuState2.getPotentialEnergy()-cpuState.getPotentialEnergy())/delta, tol)
// (3) Check whether the Reference and CPU platforms agree when using PME
nonbonded->setNonbondedMethod(NonbondedForce::PME);
cpuContext.reinitialize();
referenceContext.reinitialize();
cpuContext.setPositions(positions);
referenceContext.setPositions(positions);
cpuState = cpuContext.getState(State::Forces | State::Energy);
referenceState = referenceContext.getState(State::Forces | State::Energy);
tol = 1e-2;
for (int i = 0; i < numParticles; i++) {
ASSERT_EQUAL_VEC(referenceState.getForces()[i], cpuState.getForces()[i], tol);
}
tol = 1e-5;
ASSERT_EQUAL_TOL(referenceState.getPotentialEnergy(), cpuState.getPotentialEnergy(), tol);
// (4) Check whether PME method in CPU is self-consistent
norm = 0.0;
for (int i = 0; i < numParticles; ++i) {
Vec3 f = cpuState.getForces()[i];
norm += f[0]*f[0] + f[1]*f[1] + f[2]*f[2];
}
norm = std::sqrt(norm);
step = delta/norm;
for (int i = 0; i < numParticles; ++i) {
Vec3 p = positions[i];
Vec3 f = cpuState.getForces()[i];
positions[i] = Vec3(p[0]-f[0]*step, p[1]-f[1]*step, p[2]-f[2]*step);
}
VerletIntegrator integrator4(0.01);
Context cpuContext3(system, integrator4, platform);
cpuContext3.setPositions(positions);
tol = 1e-2;
State cpuState3 = cpuContext3.getState(State::Energy);
ASSERT_EQUAL_TOL(norm, (cpuState3.getPotentialEnergy()-cpuState.getPotentialEnergy())/delta, tol)
}
void testSerialization() {
// Create a Force.
NonbondedForce force;
force.setForceGroup(3);
force.setNonbondedMethod(NonbondedForce::CutoffPeriodic);
force.setSwitchingDistance(1.5);
force.setUseSwitchingFunction(true);
force.setCutoffDistance(2.0);
force.setEwaldErrorTolerance(1e-3);
force.setReactionFieldDielectric(50.0);
force.setUseDispersionCorrection(false);
double alpha = 0.5;
int nx = 3, ny = 5, nz = 7;
force.setPMEParameters(alpha, nx, ny, nz);
double dalpha = 0.8;
int dnx = 4, dny = 6, dnz = 7;
force.setLJPMEParameters(dalpha, dnx, dny, dnz);
force.addParticle(1, 0.1, 0.01);
force.addParticle(0.5, 0.2, 0.02);
force.addParticle(-0.5, 0.3, 0.03);
force.addException(0, 1, 2, 0.5, 0.1);
force.addException(1, 2, 0.2, 0.4, 0.2);
force.addGlobalParameter("scale1", 1.0);
force.addGlobalParameter("scale2", 2.0);
force.addParticleParameterOffset("scale1", 2, 1.5, 2.0, 2.5);
force.addExceptionParameterOffset("scale2", 1, -0.1, -0.2, -0.3);
// Serialize and then deserialize it.
stringstream buffer;
XmlSerializer::serialize<NonbondedForce>(&force, "Force", buffer);
NonbondedForce* copy = XmlSerializer::deserialize<NonbondedForce>(buffer);
// Compare the two forces to see if they are identical.
NonbondedForce& force2 = *copy;
ASSERT_EQUAL(force.getForceGroup(), force2.getForceGroup());
ASSERT_EQUAL(force.getNonbondedMethod(), force2.getNonbondedMethod());
ASSERT_EQUAL(force.getSwitchingDistance(), force2.getSwitchingDistance());
ASSERT_EQUAL(force.getUseSwitchingFunction(), force2.getUseSwitchingFunction());
ASSERT_EQUAL(force.getCutoffDistance(), force2.getCutoffDistance());
ASSERT_EQUAL(force.getEwaldErrorTolerance(), force2.getEwaldErrorTolerance());
ASSERT_EQUAL(force.getReactionFieldDielectric(), force2.getReactionFieldDielectric());
ASSERT_EQUAL(force.getUseDispersionCorrection(), force2.getUseDispersionCorrection());
ASSERT_EQUAL(force.getNumParticles(), force2.getNumParticles());
ASSERT_EQUAL(force.getNumExceptions(), force2.getNumExceptions());
ASSERT_EQUAL(force.getNumGlobalParameters(), force2.getNumGlobalParameters());
ASSERT_EQUAL(force.getNumParticleParameterOffsets(), force2.getNumParticleParameterOffsets());
ASSERT_EQUAL(force.getNumExceptionParameterOffsets(), force2.getNumExceptionParameterOffsets());
double alpha2;
int nx2, ny2, nz2;
force2.getPMEParameters(alpha2, nx2, ny2, nz2);
ASSERT_EQUAL(alpha, alpha2);
ASSERT_EQUAL(nx, nx2);
ASSERT_EQUAL(ny, ny2);
ASSERT_EQUAL(nz, nz2);
double dalpha2;
int dnx2, dny2, dnz2;
force2.getLJPMEParameters(dalpha2, dnx2, dny2, dnz2);
ASSERT_EQUAL(dalpha, dalpha2);
ASSERT_EQUAL(dnx, dnx2);
ASSERT_EQUAL(dny, dny2);
ASSERT_EQUAL(dnz, dnz2);
for (int i = 0; i < force.getNumGlobalParameters(); i++) {
ASSERT_EQUAL(force.getGlobalParameterName(i), force2.getGlobalParameterName(i));
ASSERT_EQUAL(force.getGlobalParameterDefaultValue(i), force2.getGlobalParameterDefaultValue(i));
}
for (int i = 0; i < force.getNumParticleParameterOffsets(); i++) {
int index1, index2;
string param1, param2;
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getParticleParameterOffset(i, param1, index1, charge1, sigma1, epsilon1);
force2.getParticleParameterOffset(i, param2, index2, charge2, sigma2, epsilon2);
ASSERT_EQUAL(index1, index1);
ASSERT_EQUAL(param1, param2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
for (int i = 0; i < force.getNumExceptionParameterOffsets(); i++) {
int index1, index2;
string param1, param2;
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getExceptionParameterOffset(i, param1, index1, charge1, sigma1, epsilon1);
force2.getExceptionParameterOffset(i, param2, index2, charge2, sigma2, epsilon2);
ASSERT_EQUAL(index1, index1);
ASSERT_EQUAL(param1, param2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
for (int i = 0; i < force.getNumParticles(); i++) {
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getParticleParameters(i, charge1, sigma1, epsilon1);
force2.getParticleParameters(i, charge2, sigma2, epsilon2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
ASSERT_EQUAL(force.getNumExceptions(), force2.getNumExceptions());
for (int i = 0; i < force.getNumExceptions(); i++) {
int a1, a2, b1, b2;
double charge1, sigma1, epsilon1;
double charge2, sigma2, epsilon2;
force.getExceptionParameters(i, a1, b1, charge1, sigma1, epsilon1);
force2.getExceptionParameters(i, a2, b2, charge2, sigma2, epsilon2);
ASSERT_EQUAL(a1, a2);
ASSERT_EQUAL(b1, b2);
ASSERT_EQUAL(charge1, charge2);
ASSERT_EQUAL(sigma1, sigma2);
ASSERT_EQUAL(epsilon1, epsilon2);
}
}
void ReferenceCalcMBPolElectrostaticsForceKernel::initialize(const OpenMM::System& system, const MBPolElectrostaticsForce& force) {
numElectrostatics = force.getNumElectrostatics();
charges.resize(numElectrostatics);
tholes.resize(5*numElectrostatics);
dampingFactors.resize(numElectrostatics);
polarity.resize(numElectrostatics);
axisTypes.resize(numElectrostatics);
multipoleAtomZs.resize(numElectrostatics);
multipoleAtomXs.resize(numElectrostatics);
multipoleAtomYs.resize(numElectrostatics);
multipoleAtomCovalentInfo.resize(numElectrostatics);
int dipoleIndex = 0;
int quadrupoleIndex = 0;
int tholeIndex = 0;
int maxCovalentRange = 0;
double totalCharge = 0.0;
for( int ii = 0; ii < numElectrostatics; ii++ ){
// multipoles
int axisType, multipoleAtomZ, multipoleAtomX, multipoleAtomY;
double charge, dampingFactorD, polarityD;
std::vector<double> dipolesD;
std::vector<double> tholesD;
force.getElectrostaticsParameters(ii, charge, axisType, multipoleAtomZ, multipoleAtomX, multipoleAtomY,
tholesD, dampingFactorD, polarityD );
totalCharge += charge;
axisTypes[ii] = axisType;
multipoleAtomZs[ii] = multipoleAtomZ;
multipoleAtomXs[ii] = multipoleAtomX;
multipoleAtomYs[ii] = multipoleAtomY;
charges[ii] = static_cast<RealOpenMM>(charge);
dampingFactors[ii] = static_cast<RealOpenMM>(dampingFactorD);
polarity[ii] = static_cast<RealOpenMM>(polarityD);
tholes[tholeIndex++] = static_cast<RealOpenMM>(tholesD[0]);
tholes[tholeIndex++] = static_cast<RealOpenMM>(tholesD[1]);
tholes[tholeIndex++] = static_cast<RealOpenMM>(tholesD[2]);
tholes[tholeIndex++] = static_cast<RealOpenMM>(tholesD[3]);
tholes[tholeIndex++] = static_cast<RealOpenMM>(tholesD[4]);
// covalent info
std::vector< std::vector<int> > covalentLists;
force.getCovalentMaps(ii, covalentLists );
multipoleAtomCovalentInfo[ii] = covalentLists;
}
polarizationType = force.getPolarizationType();
if( polarizationType == MBPolElectrostaticsForce::Mutual ){
mutualInducedMaxIterations = force.getMutualInducedMaxIterations();
mutualInducedTargetEpsilon = force.getMutualInducedTargetEpsilon();
}
includeChargeRedistribution = force.getIncludeChargeRedistribution();
// PME
nonbondedMethod = force.getNonbondedMethod();
if( nonbondedMethod == MBPolElectrostaticsForce::PME ){
usePme = true;
alphaEwald = force.getAEwald();
cutoffDistance = force.getCutoffDistance();
force.getPmeGridDimensions(pmeGridDimension);
if (pmeGridDimension[0] == 0 || alphaEwald == 0.0) {
NonbondedForce nb;
nb.setEwaldErrorTolerance(force.getEwaldErrorTolerance());
nb.setCutoffDistance(force.getCutoffDistance());
int gridSizeX, gridSizeY, gridSizeZ;
NonbondedForceImpl::calcPMEParameters(system, nb, alphaEwald, gridSizeX, gridSizeY, gridSizeZ);
pmeGridDimension[0] = gridSizeX;
pmeGridDimension[1] = gridSizeY;
pmeGridDimension[2] = gridSizeZ;
std::cout << "Computed PME parameters for MBPolElectrostaticsForce, alphaEwald:" <<
alphaEwald << " pmeGrid: " << gridSizeX << "," << gridSizeY << ","<< gridSizeZ << std::endl;
}
} else {
usePme = false;
}
return;
}
void testPME(bool triclinic) {
// Create a cloud of random point charges.
const int numParticles = 51;
const double boxWidth = 5.0;
const double cutoff = 1.0;
Vec3 boxVectors[3];
if (triclinic) {
boxVectors[0] = Vec3(boxWidth, 0, 0);
boxVectors[1] = Vec3(0.2*boxWidth, boxWidth, 0);
boxVectors[2] = Vec3(-0.3*boxWidth, -0.1*boxWidth, boxWidth);
}
else {
boxVectors[0] = Vec3(boxWidth, 0, 0);
boxVectors[1] = Vec3(0, boxWidth, 0);
boxVectors[2] = Vec3(0, 0, boxWidth);
}
System system;
system.setDefaultPeriodicBoxVectors(boxVectors[0], boxVectors[1], boxVectors[2]);
NonbondedForce* force = new NonbondedForce();
system.addForce(force);
vector<Vec3> positions(numParticles);
OpenMM_SFMT::SFMT sfmt;
init_gen_rand(0, sfmt);
for (int i = 0; i < numParticles; i++) {
system.addParticle(1.0);
force->addParticle(-1.0+i*2.0/(numParticles-1), 1.0, 0.0);
positions[i] = Vec3(boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt), boxWidth*genrand_real2(sfmt));
}
force->setNonbondedMethod(NonbondedForce::PME);
force->setCutoffDistance(cutoff);
force->setReciprocalSpaceForceGroup(1);
force->setEwaldErrorTolerance(1e-4);
// Compute the reciprocal space forces with the reference platform.
Platform& platform = Platform::getPlatformByName("Reference");
VerletIntegrator integrator(0.01);
Context context(system, integrator, platform);
context.setPositions(positions);
State refState = context.getState(State::Forces | State::Energy, false, 1<<1);
// Now compute them with the optimized kernel.
double alpha;
int gridx, gridy, gridz;
NonbondedForceImpl::calcPMEParameters(system, *force, alpha, gridx, gridy, gridz, false);
CpuCalcPmeReciprocalForceKernel pme(CalcPmeReciprocalForceKernel::Name(), platform);
IO io;
double sumSquaredCharges = 0;
for (int i = 0; i < numParticles; i++) {
io.posq.push_back(positions[i][0]);
io.posq.push_back(positions[i][1]);
io.posq.push_back(positions[i][2]);
double charge, sigma, epsilon;
force->getParticleParameters(i, charge, sigma, epsilon);
io.posq.push_back(charge);
sumSquaredCharges += charge*charge;
}
double ewaldSelfEnergy = -ONE_4PI_EPS0*alpha*sumSquaredCharges/sqrt(M_PI);
pme.initialize(gridx, gridy, gridz, numParticles, alpha, true);
pme.beginComputation(io, boxVectors, true);
double energy = pme.finishComputation(io);
// See if they match.
ASSERT_EQUAL_TOL(refState.getPotentialEnergy(), energy+ewaldSelfEnergy, 1e-3);
for (int i = 0; i < numParticles; i++)
ASSERT_EQUAL_VEC(refState.getForces()[i], Vec3(io.force[4*i], io.force[4*i+1], io.force[4*i+2]), 1e-3);
}
void testEwaldPME() {
double tol = 1e-5;
const double boxSize = 3.00646;
const double cutoff = 1.2;
const int numParticles = 894;
// Use amorphous NaCl system
// The particles are simple charges, no VdW interactions
ReferencePlatform platform;
System system;
for (int i = 0; i < numParticles/2; i++)
system.addParticle(22.99);
for (int i = 0; i < numParticles/2; i++)
system.addParticle(35.45);
VerletIntegrator integrator(0.01);
NonbondedForce* nonbonded = new NonbondedForce();
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(1.0, 1.0,0.0);
for (int i = 0; i < numParticles/2; i++)
nonbonded->addParticle(-1.0, 1.0,0.0);
nonbonded->setNonbondedMethod(NonbondedForce::Ewald);
nonbonded->setCutoffDistance(cutoff);
system.setDefaultPeriodicBoxVectors(Vec3(boxSize, 0, 0), Vec3(0, boxSize, 0), Vec3(0, 0, boxSize));
nonbonded->setEwaldErrorTolerance(EWALD_TOL);
system.addForce(nonbonded);
Context context(system, integrator, platform);
vector<Vec3> positions(numParticles);
#include "nacl_amorph.dat"
context.setPositions(positions);
State state1 = context.getState(State::Forces | State::Energy);
const vector<Vec3>& forces1 = state1.getForces();
// (1) CHECK EXACT VALUE OF EWALD ENERGY (Against Gromacs output)
tol = 1e-4;
ASSERT_EQUAL_TOL(-3.82047e+05, state1.getPotentialEnergy(), tol);
// (2) CHECK WHETHER THE EWALD FORCES ARE THE SAME AS THE GROMACS OUTPUT
// these are forces for alpha: 2.82756, kmax(x/y/z) = 11
tol = 1e-2;
// #include "nacl_amorph_GromacsForcesEwald.dat"
// (3) CHECK SELF-CONSISTENCY
// Take a small step in the direction of the energy gradient.
double norm = 0.0;
for (int i = 0; i < numParticles; ++i) {
Vec3 f = state1.getForces()[i];
norm += f[0]*f[0] + f[1]*f[1] + f[2]*f[2];
}
norm = std::sqrt(norm);
const double delta = 1e-2;
double step = delta/norm;
for (int i = 0; i < numParticles; ++i) {
Vec3 p = positions[i];
Vec3 f = state1.getForces()[i];
positions[i] = Vec3(p[0]-f[0]*step, p[1]-f[1]*step, p[2]-f[2]*step);
}
context.setPositions(positions);
// See whether the potential energy changed by the expected amount.
State state2 = context.getState(State::Energy);
ASSERT_EQUAL_TOL(norm, (state2.getPotentialEnergy()-state1.getPotentialEnergy())/delta, fabs(EWALD_TOL*state2.getPotentialEnergy()/(state2.getPotentialEnergy()-state1.getPotentialEnergy())))
// (4) CHECK EXACT VALUE OF PME ENERGY
nonbonded->setNonbondedMethod(NonbondedForce::PME);
nonbonded->setEwaldErrorTolerance(PME_TOL);
context.reinitialize();
#include "nacl_amorph.dat"
context.setPositions(positions);
State state3 = context.getState(State::Forces | State::Energy);
// Gromacs PME energy for the same mesh
tol = 1e-4;
ASSERT_EQUAL_TOL(-3.82047e+05, state3.getPotentialEnergy(), tol);
// (5) CHECK WHETHER PME FORCES ARE THE SAME AS THE GROMACS OUTPUT USING EWALD
tol = 1e-1;
// #include "nacl_amorph_GromacsForcesEwald.dat"
// (6) CHECK PME FOR SELF-CONSISTENCY
// Take a small step in the direction of the energy gradient.
norm = 0.0;
for (int i = 0; i < numParticles; ++i) {
Vec3 f = state3.getForces()[i];
norm += f[0]*f[0] + f[1]*f[1] + f[2]*f[2];
}
norm = std::sqrt(norm);
step = delta/norm;
for (int i = 0; i < numParticles; ++i) {
Vec3 p = positions[i];
Vec3 f = state3.getForces()[i];
positions[i] = Vec3(p[0]-f[0]*step, p[1]-f[1]*step, p[2]-f[2]*step);
}
context.setPositions(positions);
// See whether the potential energy changed by the expected amount.
State state4 = context.getState(State::Energy);
ASSERT_EQUAL_TOL(norm, (state4.getPotentialEnergy()-state3.getPotentialEnergy())/delta, fabs(PME_TOL*state4.getPotentialEnergy()/(state4.getPotentialEnergy()-state3.getPotentialEnergy())))
}
