void* CMAPTorsionForceProxy::deserialize(const SerializationNode& node) const {
if (node.getIntProperty("version") != 1)
throw OpenMMException("Unsupported version number");
CMAPTorsionForce* force = new CMAPTorsionForce();
try {
const SerializationNode& maps = node.getChildNode("Maps");
for (int i = 0; i < (int) maps.getChildren().size(); i++) {
const SerializationNode& map = maps.getChildren()[i];
int size = map.getIntProperty("size");
if (size*size != map.getChildren().size())
throw OpenMMException("Wrong number of values specified for CMAP");
vector<double> energy(size*size);
for (int j = 0; j < (int) energy.size(); j++)
energy[j] = map.getChildren()[j].getDoubleProperty("e");
force->addMap(size, energy);
}
const SerializationNode& torsions = node.getChildNode("Torsions");
for (int i = 0; i < (int) torsions.getChildren().size(); i++) {
const SerializationNode& torsion = torsions.getChildren()[i];
force->addTorsion(torsion.getIntProperty("map"), torsion.getIntProperty("a1"), torsion.getIntProperty("a2"), torsion.getIntProperty("a3"), torsion.getIntProperty("a4"),
torsion.getIntProperty("b1"), torsion.getIntProperty("b2"), torsion.getIntProperty("b3"), torsion.getIntProperty("b4"));
}
}
catch (...) {
delete force;
throw;
}
return force;
}
void testChangingParameters() {
// Create a system with two maps and one torsion.
const int mapSize = 8;
System system;
for (int i = 0; i < 5; i++)
system.addParticle(1.0);
CMAPTorsionForce* cmap = new CMAPTorsionForce();
vector<double> mapEnergy1(mapSize*mapSize);
vector<double> mapEnergy2(mapSize*mapSize);
for (int i = 0; i < mapSize; i++) {
double angle1 = i*2*M_PI/mapSize;
double energy1 = cos(angle1);
for (int j = 0; j < mapSize; j++) {
double angle2 = j*2*M_PI/mapSize;
double energy2 = 10*sin(angle2);
mapEnergy1[i+j*mapSize] = energy1+energy2;
mapEnergy2[i+j*mapSize] = energy1-energy2;
}
}
cmap->addMap(mapSize, mapEnergy1);
cmap->addMap(mapSize, mapEnergy2);
cmap->addTorsion(0, 0, 1, 2, 3, 1, 2, 3, 4);
system.addForce(cmap);
// Set particle positions so angle1=0 and angle2=PI/4.
vector<Vec3> positions(5);
positions[0] = Vec3(0, 0, 1);
positions[1] = Vec3(0, 0, 0);
positions[2] = Vec3(1, 0, 0);
positions[3] = Vec3(1, 0, 1);
positions[4] = Vec3(0.5, -0.5, 1);
VerletIntegrator integrator(0.01);
Context context(system, integrator, platform);
context.setPositions(positions);
// Check that the energy is correct.
double energy = context.getState(State::Energy).getPotentialEnergy();
ASSERT_EQUAL_TOL(1+10*sin(M_PI/4), energy, 1e-5);
// Modify the parameters.
cmap->setTorsionParameters(0, 1, 0, 1, 2, 3, 1, 2, 3, 4);
for (int i = 0; i < mapSize*mapSize; i++)
mapEnergy2[i] *= 2.0;
cmap->setMapParameters(1, mapSize, mapEnergy2);
cmap->updateParametersInContext(context);
// See if the results are correct.
energy = context.getState(State::Energy).getPotentialEnergy();
ASSERT_EQUAL_TOL(2-20*sin(M_PI/4), energy, 1e-5);
}
void testCMAPTorsions() {
const int mapSize = 36;
// Create two systems: one with a pair of periodic torsions, and one with a CMAP torsion
// that approximates the same force.
System system1;
for (int i = 0; i < 5; i++)
system1.addParticle(1.0);
PeriodicTorsionForce* periodic = new PeriodicTorsionForce();
periodic->addTorsion(0, 1, 2, 3, 2, M_PI/4, 1.5);
periodic->addTorsion(1, 2, 3, 4, 3, M_PI/3, 2.0);
system1.addForce(periodic);
System system2;
for (int i = 0; i < 5; i++)
system2.addParticle(1.0);
CMAPTorsionForce* cmap = new CMAPTorsionForce();
vector<double> mapEnergy(mapSize*mapSize);
for (int i = 0; i < mapSize; i++) {
double angle1 = i*2*M_PI/mapSize;
double energy1 = 1.5*(1+cos(2*angle1-M_PI/4));
for (int j = 0; j < mapSize; j++) {
double angle2 = j*2*M_PI/mapSize;
double energy2 = 2.0*(1+cos(3*angle2-M_PI/3));
mapEnergy[i+j*mapSize] = energy1+energy2;
}
}
cmap->addMap(mapSize, mapEnergy);
cmap->addTorsion(0, 0, 1, 2, 3, 1, 2, 3, 4);
system2.addForce(cmap);
// Set the atoms in various positions, and verify that both systems give equal forces and energy.
OpenMM_SFMT::SFMT sfmt;
init_gen_rand(0, sfmt);
vector<Vec3> positions(5);
VerletIntegrator integrator1(0.01);
VerletIntegrator integrator2(0.01);
Context c1(system1, integrator1, platform);
Context c2(system2, integrator2, platform);
for (int i = 0; i < 50; i++) {
for (int j = 0; j < (int) positions.size(); j++)
positions[j] = Vec3(5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt));
c1.setPositions(positions);
c2.setPositions(positions);
State s1 = c1.getState(State::Forces | State::Energy);
State s2 = c2.getState(State::Forces | State::Energy);
for (int i = 0; i < system1.getNumParticles(); i++)
ASSERT_EQUAL_VEC(s1.getForces()[i], s2.getForces()[i], 0.05);
ASSERT_EQUAL_TOL(s1.getPotentialEnergy(), s2.getPotentialEnergy(), 1e-3);
}
}