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36 * \brief Defines Andersen temperature coupling for the modular simulator
38 * \author Pascal Merz <pascal.merz@me.com>
39 * \ingroup module_modularsimulator
42 #include "andersentemperaturecoupling.h"
46 #include "gromacs/domdec/domdec_struct.h"
47 #include "gromacs/math/functions.h"
48 #include "gromacs/math/units.h"
49 #include "gromacs/mdlib/constr.h"
50 #include "gromacs/mdlib/mdatoms.h"
51 #include "gromacs/mdlib/stat.h"
52 #include "gromacs/mdtypes/commrec.h"
53 #include "gromacs/mdtypes/inputrec.h"
54 #include "gromacs/mdtypes/mdatom.h"
55 #include "gromacs/mdrun/isimulator.h"
56 #include "gromacs/random/tabulatednormaldistribution.h"
57 #include "gromacs/random/threefry.h"
58 #include "gromacs/random/uniformrealdistribution.h"
60 #include "compositesimulatorelement.h"
61 #include "constraintelement.h"
62 #include "simulatoralgorithm.h"
63 #include "statepropagatordata.h"
67 AndersenTemperatureCoupling::AndersenTemperatureCoupling(double simulationTimestep,
70 ArrayRef<const real> referenceTemperature,
71 ArrayRef<const real> couplingTime,
72 StatePropagatorData* statePropagatorData,
73 const MDAtoms* mdAtoms,
74 const t_commrec* cr) :
75 doMassive_(doMassive),
76 randomizationRate_(simulationTimestep / couplingTime[0]),
77 couplingFrequency_(doMassive ? roundToInt(1. / randomizationRate_) : 1),
79 referenceTemperature_(referenceTemperature),
80 couplingTime_(couplingTime),
81 statePropagatorData_(statePropagatorData),
82 mdAtoms_(mdAtoms->mdatoms()),
87 void AndersenTemperatureCoupling::scheduleTask(Step step,
89 const RegisterRunFunction& registerRunFunction)
91 if (do_per_step(step, couplingFrequency_))
93 registerRunFunction([this, step]() { apply(step); });
97 void AndersenTemperatureCoupling::apply(Step step)
99 ThreeFry2x64<0> rng(seed_, RandomDomain::Thermostat);
100 UniformRealDistribution<real> uniformDist;
101 TabulatedNormalDistribution<real, 14> normalDist;
103 const bool doDomainDecomposition = DOMAINDECOMP(cr_);
105 auto velocities = statePropagatorData_->velocitiesView().unpaddedArrayRef();
107 for (int atomIdx = 0; atomIdx < mdAtoms_->homenr; ++atomIdx)
109 const int temperatureGroup = mdAtoms_->cTC ? mdAtoms_->cTC[atomIdx] : 0;
110 if (referenceTemperature_[temperatureGroup] <= 0 || couplingTime_[temperatureGroup] <= 0)
115 const int globalAtomIdx = doDomainDecomposition ? cr_->dd->globalAtomIndices[atomIdx] : atomIdx;
116 rng.restart(step, globalAtomIdx);
118 // For massive Andersen, this function is only called periodically, but we apply each time
119 // Otherwise, this function is called every step, but we randomize atoms probabilistically
124 if (doMassive_ || (uniformDist(rng) < randomizationRate_))
126 const real scalingFactor = std::sqrt(c_boltz * referenceTemperature_[temperatureGroup]
127 * mdAtoms_->invmass[atomIdx]);
129 for (int d = 0; d < DIM; d++)
131 velocities[atomIdx][d] = scalingFactor * normalDist(rng);
137 int AndersenTemperatureCoupling::frequency() const
139 return couplingFrequency_;
142 void AndersenTemperatureCoupling::updateReferenceTemperature(ArrayRef<const real> gmx_unused temperatures,
143 ReferenceTemperatureChangeAlgorithm gmx_unused algorithm)
145 // Currently, we don't know about any temperature change algorithms, so we assert this never gets called
146 GMX_ASSERT(false, "AndersenTemperatureCoupling: Unknown ReferenceTemperatureChangeAlgorithm.");
149 void AndersenTemperatureCoupling::elementSetup() {}
150 ISimulatorElement* AndersenTemperatureCoupling::getElementPointerImpl(
151 LegacySimulatorData* legacySimulatorData,
152 ModularSimulatorAlgorithmBuilderHelper* builderHelper,
153 StatePropagatorData* statePropagatorData,
154 EnergyData* energyData,
155 FreeEnergyPerturbationData* freeEnergyPerturbationData,
156 GlobalCommunicationHelper gmx_unused* globalCommunicationHelper,
157 ObservablesReducer gmx_unused* observablesReducer)
159 GMX_RELEASE_ASSERT(legacySimulatorData->inputrec->etc == TemperatureCoupling::Andersen
160 || legacySimulatorData->inputrec->etc == TemperatureCoupling::AndersenMassive,
161 "Expected the thermostat type to be andersen or andersen-massive.");
162 auto andersenThermostat = std::make_unique<AndersenTemperatureCoupling>(
163 legacySimulatorData->inputrec->delta_t,
164 legacySimulatorData->inputrec->etc == TemperatureCoupling::AndersenMassive,
165 legacySimulatorData->inputrec->andersen_seed,
166 constArrayRefFromArray(legacySimulatorData->inputrec->opts.ref_t,
167 legacySimulatorData->inputrec->opts.ngtc),
168 constArrayRefFromArray(legacySimulatorData->inputrec->opts.tau_t,
169 legacySimulatorData->inputrec->opts.ngtc),
171 legacySimulatorData->mdAtoms,
172 legacySimulatorData->cr);
173 auto* andersenThermostatPtr = andersenThermostat.get();
174 builderHelper->registerReferenceTemperatureUpdate(
175 [andersenThermostatPtr](ArrayRef<const real> temperatures,
176 ReferenceTemperatureChangeAlgorithm algorithm) {
177 andersenThermostatPtr->updateReferenceTemperature(temperatures, algorithm);
180 // T-coupling frequency will be composite element frequency
181 const auto frequency = andersenThermostat->frequency();
182 // Set up call list for composite element
183 std::vector<compat::not_null<ISimulatorElement*>> elementCallList = { compat::make_not_null(
184 andersenThermostat.get()) };
185 // Set up element list for composite element
186 std::vector<std::unique_ptr<gmx::ISimulatorElement>> elements;
187 elements.emplace_back(std::move(andersenThermostat));
189 // If there are constraints, add constraint element after Andersen element
190 if (legacySimulatorData->constr)
192 // This is excluded in preprocessing -
193 // asserted here to make sure things don't get out of sync
195 legacySimulatorData->inputrec->etc == TemperatureCoupling::AndersenMassive,
196 "Per-particle Andersen thermostat is not implemented for systems with constrains.");
197 // Build constraint element
198 auto constraintElement = std::make_unique<ConstraintsElement<ConstraintVariable::Velocities>>(
199 legacySimulatorData->constr,
202 freeEnergyPerturbationData,
203 MASTER(legacySimulatorData->cr),
204 legacySimulatorData->fplog,
205 legacySimulatorData->inputrec,
206 legacySimulatorData->mdAtoms->mdatoms());
207 // Add call to composite element call list
208 elementCallList.emplace_back(compat::make_not_null(constraintElement.get()));
209 // Move ownership of constraint element to composite element
210 elements.emplace_back(std::move(constraintElement));
213 // Store composite element in builder helper and return pointer
214 return builderHelper->storeElement(std::make_unique<CompositeSimulatorElement>(
215 std::move(elementCallList), std::move(elements), frequency));