test12.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 "MPIchemps2.h"

using namespace std;

int main(void){

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

   CheMPS2::Initialize::Init();

   const int L = 8; //Number of single-particle states
   double eps[] = { -3.5, -2.5, -1.5, -0.5, 0.5, 1.5, 2.5, 3.5 };
   const double g = -1.0;
   const double power = 0.0;

   const int N = L;     //Number of fermions in the model
   const int TwoS = 0;  //Twice the total spin
   const int Irrep = 0; //No point group is used, Irrep should ALWAYS be zero.

   //The convergence scheme
   CheMPS2::ConvergenceScheme * OptScheme = new CheMPS2::ConvergenceScheme(2);
   //OptScheme->setInstruction(instruction, DSU(2), Econvergence, maxSweeps, noisePrefactor);
   OptScheme->setInstruction(0,  100, 1e-10, 10, 0.5 );
   OptScheme->setInstruction(1, 1000, 1e-10, 10, 0.0 );

   /*
   Model: h_ij = delta_ij eps[i]
          v_ijkl = delta_ij delta_kl g ( eps[i] * eps[k] ) ^ {power}
          h_ijkl = v_ijkl + ( delta_ik h_jl + delta_jl h_ik ) / ( N - 1 )
          Ham = 0.5 sum_ijkl h_ijkl sum_sigma,tau a^+_{i,sigma} a^+_{j,tau} a_{l,tau} a_{k,sigma}
   */

   // C1 point group symmetry
   const int group = 0;
   int * irreps = new int[ L ];
   for ( int orb = 0; orb < L; orb++ ){ irreps[ orb ] = 0; }
   CheMPS2::Hamiltonian * Ham = new CheMPS2::Hamiltonian( L, group, irreps ); // The Hamiltonian initializes all its matrix elements to zero
   delete [] irreps;

   CheMPS2::Problem * Prob = new CheMPS2::Problem(Ham, TwoS, N, Irrep);
   CheMPS2::DMRG * theDMRG = new CheMPS2::DMRG(Prob, OptScheme); // Prob->construct_mxelem() is called now
   for ( int orb1 = 0; orb1 < L; orb1++ ){
      for ( int orb2 = 0; orb2 < L; orb2++ ){
         const double eri = g * pow( fabs( eps[ orb1 ] * eps[ orb2 ] ), power );
         const double oei = ( eps[ orb1 ] + eps[ orb2 ] ) / ( N - 1 );
         if ( orb1 == orb2 ){
            Prob->setMxElement( orb1, orb1, orb2, orb2, eri + oei );
         } else {
            Prob->setMxElement( orb1, orb1, orb2, orb2, eri );
            Prob->setMxElement( orb1, orb2, orb1, orb2, oei );
         }
      }
   }
   theDMRG->PreSolve(); // New matrix elements require reconstruction of complementary renormalized operators
   const double Energy = theDMRG->Solve();
   theDMRG->calc2DMandCorrelations();
   #ifdef CHEMPS2_MPI_COMPILATION
   if ( CheMPS2::MPIchemps2::mpi_rank() == MPI_CHEMPS2_MASTER )
   #endif
   {
      theDMRG->getCorrelations()->Print();
   }

   //Clean up DMRG
   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( Energy + 25.5134137600604 ) < 1e-8 ) ? true : false;

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

   cout << "================> Did test 12 succeed : ";
   if (success){
      cout << "yes" << endl;
      return 0; //Success
   }
   cout << "no" << endl;
   return 7; //Fail

}