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/*
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();
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;
//Calculate FCI reference energy
double EnergyFCI = 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);
EnergyFCI = theFCI->GSDavidson(NULL);
delete theFCI;
}
#ifdef CHEMPS2_MPI_COMPILATION
CheMPS2::MPIchemps2::broadcast_array_double( &EnergyFCI, 1, MPI_CHEMPS2_MASTER );
#endif
//Clean up the Hamiltonian
delete Ham;
//Check succes
const bool success = ( fabs( EnergyDMRG - EnergyFCI ) < 1e-8 ) ? true : false;
#ifdef CHEMPS2_MPI_COMPILATION
CheMPS2::MPIchemps2::mpi_finalize();
#endif
cout << "================> Did test 4 succeed : ";
if (success){
cout << "yes" << endl;
return 0; //Success
}
cout << "no" << endl;
return 7; //Fail
}
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