test11.cpp.in

/*
   CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry
   Copyright (C) 2013-2018 Sebastian Wouters

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, write to the Free Software Foundation, Inc.,
   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <iostream>
#include <math.h>

#include "Initialize.h"
#include "DMRG.h"
#include "FCI.h"
#include "MPIchemps2.h"

using namespace std;

int main(void){

   #ifdef CHEMPS2_MPI_COMPILATION
   CheMPS2::MPIchemps2::mpi_init();
   #endif

   CheMPS2::Initialize::Init();
   
   //The Hamiltonian: 1D Hubbard model
   const int L = 10;
   const int Group = 0;
   const double U = 2.0;
   const double T = -1.0;
   int * irreps = new int[L];
   for (int cnt=0; cnt<L; cnt++){ irreps[cnt] = 0; }
   //The Hamiltonian initializes all its matrix elements to 0.0
   CheMPS2::Hamiltonian * Ham = new CheMPS2::Hamiltonian(L, Group, irreps);
   delete [] irreps;
   for (int cnt=0; cnt<L; cnt++){ Ham->setVmat(cnt,cnt,cnt,cnt,U); }
   for (int cnt=0; cnt<L-1; cnt++){ Ham->setTmat(cnt,cnt+1,T); }
   
   //The targeted state
   const int TwoS = 5;
   const int N = 9;
   const int Irrep = 0;
   CheMPS2::Problem * Prob = new CheMPS2::Problem(Ham, TwoS, N, Irrep);
   
   //The convergence scheme
   CheMPS2::ConvergenceScheme * OptScheme = new CheMPS2::ConvergenceScheme(2);
   //OptScheme->setInstruction(instruction, DSU(2), Econvergence, maxSweeps, noisePrefactor);
   OptScheme->setInstruction(0,   30, 1e-10,  3, 0.1);
   OptScheme->setInstruction(1, 1000, 1e-10, 10, 0.0);
   
   //Run ground state calculation
   CheMPS2::DMRG * theDMRG = new CheMPS2::DMRG(Prob, OptScheme);
   const double EnergyDMRG = theDMRG->Solve();
   const bool do_3rdm = true;
   theDMRG->calc_rdms_and_correlations(do_3rdm);
   #ifdef CHEMPS2_MPI_COMPILATION
   if ( CheMPS2::MPIchemps2::mpi_rank() == MPI_CHEMPS2_MASTER )
   #endif
   {
      theDMRG->getCorrelations()->Print();
   }
   
   //Get a diagonal block of the 4-RDM
   const int ham_orbz = 3;
   double * dmrg_diag_4rdm = new double[ L*L*L*L*L*L ];
   theDMRG->Symm4RDM( dmrg_diag_4rdm, ham_orbz, ham_orbz, false );
   
   //Calculate FCI reference energy
   double EnergyFCI   = 0.0;
   double RMSerror2DM = 0.0;
   double RMSerror3DM = 0.0;
   double RMSerror4DM = 0.0;
   #ifdef CHEMPS2_MPI_COMPILATION
   if ( CheMPS2::MPIchemps2::mpi_rank() == MPI_CHEMPS2_MASTER )
   #endif
   {
      const int Nel_up   = ( N + TwoS ) / 2;
      const int Nel_down = ( N - TwoS ) / 2;
      const double maxMemWorkMB = 10.0;
      const int FCIverbose = 1;
      CheMPS2::FCI * theFCI = new CheMPS2::FCI(Ham, Nel_up, Nel_down, Irrep, maxMemWorkMB, FCIverbose);
      double * inoutput = new double[theFCI->getVecLength(0)];
      theFCI->FillRandom(theFCI->getVecLength(0), inoutput);
      inoutput[ theFCI->LowestEnergyDeterminant() ] = 1.0;
      EnergyFCI = theFCI->GSDavidson(inoutput);
      theFCI->CalcSpinSquared(inoutput);
      const int L = Ham->getL();
      double * RDMspace = new double[ L*L*L*L*L*L ];
      theFCI->Fill2RDM(inoutput, RDMspace);
      for (int orb1=0; orb1<L; orb1++){
         for (int orb2=0; orb2<L; orb2++){
            for (int orb3=0; orb3<L; orb3++){
               for (int orb4=0; orb4<L; orb4++){
                  const double difference = RDMspace[orb1 + L*(orb2 + L*(orb3 + L*orb4))]
                                          - theDMRG->get2DM()->getTwoDMA_HAM(orb1, orb2, orb3, orb4);
                  RMSerror2DM += difference * difference;
               }
            }
         }
      }
      theFCI->Fill3RDM(inoutput, RDMspace);
      for (int orb1=0; orb1<L; orb1++){
         for (int orb2=0; orb2<L; orb2++){
            for (int orb3=0; orb3<L; orb3++){
               for (int orb4=0; orb4<L; orb4++){
                  for (int orb5=0; orb5<L; orb5++){
                     for (int orb6=0; orb6<L; orb6++){
                        const double difference = RDMspace[orb1 + L*(orb2 + L*(orb3 + L*(orb4 + L*(orb5 + L * orb6))))]
                                                - theDMRG->get3DM()->get_ham_index(orb1, orb2, orb3, orb4, orb5, orb6);
                        RMSerror3DM += difference * difference;
                     }
                  }
               }
            }
         }
      }
      double * fci_diag_4rdm = new double[ L*L*L*L*L*L ];
      theFCI->Diag4RDM( inoutput, RDMspace, ham_orbz, fci_diag_4rdm );
      for (int orb1=0; orb1<L; orb1++){
         for (int orb2=0; orb2<L; orb2++){
            for (int orb3=0; orb3<L; orb3++){
               for (int orb4=0; orb4<L; orb4++){
                  for (int orb5=0; orb5<L; orb5++){
                     for (int orb6=0; orb6<L; orb6++){
                        const double difference = fci_diag_4rdm[orb1 + L*(orb2 + L*(orb3 + L*(orb4 + L*(orb5 + L * orb6))))]
                                         - 0.5 * dmrg_diag_4rdm[orb1 + L*(orb2 + L*(orb3 + L*(orb4 + L*(orb5 + L * orb6))))];
                        RMSerror4DM += difference * difference;
                     }
                  }
               }
            }
         }
      }
      delete [] fci_diag_4rdm;
      delete [] RDMspace;
      delete [] inoutput;
      delete theFCI;
      RMSerror2DM = sqrt(RMSerror2DM);
      RMSerror3DM = sqrt(RMSerror3DM);
      RMSerror4DM = sqrt(RMSerror4DM);
      cout << "Frobenius norm of the difference of the DMRG and FCI 2-RDM = " << RMSerror2DM << endl;
      cout << "Frobenius norm of the difference of the DMRG and FCI 3-RDM = " << RMSerror3DM << endl;
      cout << "Frobenius norm of the difference of the DMRG and FCI diag(4-RDM) for fixed orbital " << ham_orbz << " = " << RMSerror4DM << endl;
      cout << "******************************************************************" << endl;
   }
   #ifdef CHEMPS2_MPI_COMPILATION
   CheMPS2::MPIchemps2::broadcast_array_double( &EnergyFCI,   1, MPI_CHEMPS2_MASTER );
   CheMPS2::MPIchemps2::broadcast_array_double( &RMSerror2DM, 1, MPI_CHEMPS2_MASTER );
   CheMPS2::MPIchemps2::broadcast_array_double( &RMSerror3DM, 1, MPI_CHEMPS2_MASTER );
   CheMPS2::MPIchemps2::broadcast_array_double( &RMSerror4DM, 1, MPI_CHEMPS2_MASTER );
   #endif
   
   //Clean up DMRG
   delete [] dmrg_diag_4rdm;
   if (CheMPS2::DMRG_storeMpsOnDisk){ theDMRG->deleteStoredMPS(); }
   if (CheMPS2::DMRG_storeRenormOptrOnDisk){ theDMRG->deleteStoredOperators(); }
   delete theDMRG;
   delete OptScheme;
   delete Prob;
   delete Ham;
   
   //Check succes
   const bool success = (( fabs( EnergyDMRG - EnergyFCI ) < 1e-8 ) && ( RMSerror2DM < 1e-3 ) && ( RMSerror3DM < 1e-3 ) && ( RMSerror4DM < 1e-3 )) ? true : false;
   
   #ifdef CHEMPS2_MPI_COMPILATION
   CheMPS2::MPIchemps2::mpi_finalize();
   #endif
   
   cout << "================> Did test 11 succeed : ";
   if (success){
      cout << "yes" << endl;
      return 0; //Success
   }
   cout << "no" << endl;
   return 7; //Fail

}