SkPot.h

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//////////////////////////////////////////////////////////////////////////////////////
// This file is distributed under the University of Illinois/NCSA Open Source License.
// See LICENSE file in top directory for details.
//
// Copyright (c) 2016 Jeongnim Kim and QMCPACK developers.
//
// File developed by: Jeremy McMinnis, jmcminis@gmail.com, University of Illinois at Urbana-Champaign
//                    Mark A. Berrill, berrillma@ornl.gov, Oak Ridge National Laboratory
//
// File created by: Jeremy McMinnis, jmcminis@gmail.com, University of Illinois at Urbana-Champaign
//////////////////////////////////////////////////////////////////////////////////////


/** @file SkPot.h
 * @brief Declare SkPot
 */
#ifndef QMCPLUSPLUS_SK_POT_H
#define QMCPLUSPLUS_SK_POT_H
#include "QMCHamiltonians/OperatorBase.h"
#include "LongRange/StructFact.h"
namespace qmcplusplus
{
/** SkPot evaluate the structure factor of the target particleset
 *
 * <estimator name="sk" type="sk" debug="no"/>
 */
class SkPot : public OperatorBase
{
public:
  SkPot(ParticleSet& elns);

  std::string getClassName() const override { return "SkPot"; }
  void resetTargetParticleSet(ParticleSet& P) override;

  [[noreturn]] Return_t evaluate(ParticleSet& P) override;

  bool put(xmlNodePtr cur) override;
  bool get(std::ostream& os) const override;
  std::unique_ptr<OperatorBase> makeClone(ParticleSet& qp, TrialWaveFunction& psi) final;

  inline void FillFk()
  {
    for (int ki = 0; ki < NumK; ki++)
    {
      RealType k = dot(sourcePtcl->getSimulationCell().getKLists().kpts_cart[ki],
                       sourcePtcl->getSimulationCell().getKLists().kpts_cart[ki]);
      k          = std::sqrt(k) - K_0;
      Fk[ki]     = OneOverN * V_0 * std::exp(-k * k);
      //         app_log()<<ki<<": "<<Fk[ki] << std::endl;
    }
  }


protected:
  ParticleSet* sourcePtcl;
  /** number of species */
  int NumSpecies;
  /** number of kpoints */
  int NumK;
  /** number of kshells */
  int MaxKshell;
  /** normalization factor */
  RealType OneOverN;
  /** kshell counters */
  std::vector<int> Kshell;
  /** instantaneous structure factor  */
  std::vector<RealType> Kmag;
  /** 1.0/degenracy for a ksell */
  std::vector<RealType> OneOverDnk;
  /** \f$rho_k = \sum_{\alpha} \rho_k^{\alpha} \f$ for species index \f$\alpha\f$ */
  Vector<ComplexType> RhokTot;
  Vector<RealType> Fk;
  RealType V_0, K_0;
  /** resize the internal data
   *
   * The argument list is not completed
   */
  void resize();

  bool hdf5_out;
};

} // namespace qmcplusplus
#endif