LatticeDeviationEstimator.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: Yubo Yang, paul.young.0414@gmail.com, University of Illinois at Urbana-Champaign
//
// File created by: Yubo Yang, paul.young.0414@gmail.com, University of Illinois at Urbana-Champaign
//////////////////////////////////////////////////////////////////////////////////////

#ifndef QMCPLUSPLUS_LATTICEDEVIATION_H
#define QMCPLUSPLUS_LATTICEDEVIATION_H

#include "Particle/ParticleSet.h"
#include "QMCHamiltonians/OperatorBase.h"
#include "ParticleBase/ParticleAttribOps.h"
#include "Particle/DistanceTable.h"

namespace qmcplusplus
{
/** lattice deviation estimator
 *
 * Compute deviation of species="tgroup" in target particle set from species="sgroup" in source particle set. The motivation is to observe the deviation of protons from their crystal sites in an all electron-proton simulation of hydrogen i.e. two-component system
   One can also create any reference point to measure the deviation of an up electron, for example
      <particleset name="wf_center">
         <group name="origin" size="1">
            <attrib name="position" datatype="posArray" condition="0">
                     0.00000000        0.00000000        0.00000000
            </attrib>
         </group>
      </particleset>
      <estimator type="latticedeviation" name="latdev" hdf5="yes" per_xyz="yes" 
           source="wf_center" sgroup="origin" target="e" tgroup="u"/> 
   This estimator outputs to both scalar.dat and stat.h5. The scalar.dat entries are averaged over all
particles, whereas the stat.h5 entries are particle-resolved. The two sets of outputs can be compared
as a consistency check for the estimator.
 */
class LatticeDeviationEstimator : public OperatorBase
{
public:
  LatticeDeviationEstimator(ParticleSet& P, ParticleSet& sP, const std::string& tgroup, const std::string& sgroup);
  ~LatticeDeviationEstimator() override {}

  std::string getClassName() const override { return "LatticeDeviationEstimator"; }
  bool put(xmlNodePtr cur) override;         // read input xml node, required
  bool get(std::ostream& os) const override; // class description, required

  Return_t evaluate(ParticleSet& P) override; // main function that calculates the observable

  // allow multiple scalars to be registered in scalar.dat
  void addObservables(PropertySetType& plist, BufferType& collectables) override;
  void setObservables(PropertySetType& plist) override;
  //void setParticlePropertyList(PropertySetType& plist, int offset); // is this method ever used?

  // make room in hdf5 observable registry
  void registerCollectables(std::vector<ObservableHelper>& h5desc, hdf_archive& file) const override;
  //void addObservables(PropertySetType& plist, BufferType& collectables); // also used for multiple scalars

  // pure virtual functions require overrider
  void resetTargetParticleSet(ParticleSet& P) override;                                   // required
  std::unique_ptr<OperatorBase> makeClone(ParticleSet& qp, TrialWaveFunction& psi) final; // required

private:
  SpeciesSet& tspecies;       // species table of target particle set
  SpeciesSet& sspecies;       // species table of source particle set
  ParticleSet &tpset, spset;  // save references to source and target particle sets
  std::string tgroup, sgroup; // name of species to track
  int num_sites;              // number of lattice sites (i.e. number of source particles)
  bool hdf5_out;              // use .h5 file for data (follow SkEstimator)
  int h5_index;               // track the starting memory location in P.Collectables
  bool per_xyz;               // track deviation in each of x,y,z directions
  std::vector<RealType> xyz2; // temporary storage for deviation in each of x,y,z directions
  xmlNodePtr input_xml;       // original xml
  // distance table ID
  const int myTableID_;
}; // LatticeDeviationEstimator

} // namespace qmcplusplus
#endif