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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 "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
}
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