FluctuatingChargePropagator.cpp

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 * SUPPORT OPEN SCIENCE!  If you use OpenMD or its source code in your
 * research, please cite the following paper when you publish your work:
 *
 * [1] Drisko et al., J. Open Source Softw. 9, 7004 (2024).
 *
 * Good starting points for code and simulation methodology are:
 *
 * [2] Meineke, et al., J. Comp. Chem. 26, 252-271 (2005).
 * [3] Fennell & Gezelter, J. Chem. Phys. 124, 234104 (2006).
 * [4] Sun, Lin & Gezelter, J. Chem. Phys. 128, 234107 (2008).
 * [5] Vardeman, Stocker & Gezelter, J. Chem. Theory Comput. 7, 834 (2011).
 * [6] Kuang & Gezelter, Mol. Phys., 110, 691-701 (2012).
 * [7] Lamichhane, Gezelter & Newman, J. Chem. Phys. 141, 134109 (2014).
 * [8] Bhattarai, Newman & Gezelter, Phys. Rev. B 99, 094106 (2019).
 * [9] Drisko & Gezelter, J. Chem. Theory Comput. 20, 4986-4997 (2024).
 */
 
#include "flucq/FluctuatingChargePropagator.hpp"
 
#ifdef IS_MPI
#include <mpi.h>
#endif
 
#include "flucq/FluctuatingChargeObjectiveFunction.hpp"
#include "optimization/Constraint.hpp"
#include "optimization/EndCriteria.hpp"
#include "optimization/OptimizationFactory.hpp"
#include "optimization/Problem.hpp"
#include "optimization/StatusFunction.hpp"
 
using namespace QuantLib;
namespace OpenMD {
 
  FluctuatingChargePropagator::FluctuatingChargePropagator(SimInfo* info) :
      info_(info), forceMan_(NULL), hasFlucQ_(false), initialized_(false) {
    Globals* simParams = info_->getSimParams();
    fqParams_          = simParams->getFluctuatingChargeParameters();
  }
 
  FluctuatingChargePropagator::~FluctuatingChargePropagator() {
    if (info_->usesFluctuatingCharges() && info_->getNFluctuatingCharges() > 0)
      delete fqConstraints_;
  }
 
  void FluctuatingChargePropagator::setForceManager(ForceManager* forceMan) {
    forceMan_ = forceMan;
  }
 
  void FluctuatingChargePropagator::initialize() {
    if (info_->usesFluctuatingCharges()) {
      if (info_->getNFluctuatingCharges() > 0) {
        hasFlucQ_      = true;
        fqConstraints_ = new FluctuatingChargeConstraints(info_);
        fqConstraints_->setConstrainRegions(fqParams_->getConstrainRegions());
      }
    }
 
    if (!hasFlucQ_) {
      initialized_ = true;
      return;
    }
 
    // SimInfo::MoleculeIterator i;
    // Molecule::FluctuatingChargeIterator  j;
    // Molecule* mol;
    // Atom* atom;
    //
    // For single-minima flucq, this ensures a net neutral system, but
    // for multiple minima, this is no longer the right thing to do:
    //
    // for (mol = info_->beginMolecule(i); mol != NULL;
    //      mol = info_->nextMolecule(i)) {
    //   for (atom = mol->beginFluctuatingCharge(j); atom != NULL;
    //        atom = mol->nextFluctuatingCharge(j)) {
    //     atom->setFlucQPos(0.0);
    //     atom->setFlucQVel(0.0);
    //   }
    // }
 
    if (fqParams_->getDoInitialOptimization()) {
      FluctuatingChargeObjectiveFunction flucQobjf(info_, forceMan_,
                                                   fqConstraints_);
 
      DynamicVector<RealType> initCoords = flucQobjf.setInitialCoords();
 
      NoConstraint noConstraint {};
      NoStatus noStatus {};
 
      Problem problem(flucQobjf, noConstraint, noStatus, initCoords);
 
      int maxIter              = fqParams_->getMaxIterations();
      RealType tolerance       = fqParams_->getTolerance();
      RealType initialStepSize = fqParams_->getInitialStepSize();
 
      EndCriteria endCriteria(maxIter, maxIter, tolerance, tolerance,
                              tolerance);
      std::string chargeOptMethod = fqParams_->getChargeOptimizationMethod();
      OptimizationMethod* minim =
          OptimizationFactory::getInstance().createOptimization(chargeOptMethod,
                                                                info_);
 
      minim->minimize(problem, endCriteria, initialStepSize);
 
      delete minim;
    }
 
    initialized_ = true;
  }
 
  void FluctuatingChargePropagator::applyConstraints() {
    if (!initialized_) initialize();
    if (!hasFlucQ_) return;
 
    fqConstraints_->applyConstraints();
  }
}  // namespace OpenMD