double CheMPS2::DMRG::solve_site( const int index, const double dvdson_rtol, const double noise_level, const int virtual_dimension, const bool am_i_master, const bool moving_right, const bool change ){
struct timeval start, end;
// Construct two-site object S. Each MPI process joins the MPS tensors. Before a matrix-vector multiplication the vector is broadcasted anyway.
gettimeofday( &start, NULL );
Sobject * denS = new Sobject( index, denBK );
denS->Join( MPS[ index ], MPS[ index + 1 ] );
gettimeofday( &end, NULL );
timings[ CHEMPS2_TIME_S_JOIN ] += ( end.tv_sec - start.tv_sec ) + 1e-6 * ( end.tv_usec - start.tv_usec );
// Feed everything to the solver. Each MPI process returns the correct energy. Only MPI_CHEMPS2_MASTER has the correct denS solution.
gettimeofday( &start, NULL );
Heff Solver( denBK, Prob, dvdson_rtol );
double ** VeffTilde = NULL;
if ( Exc_activated ){ VeffTilde = prepare_excitations( denS ); }
double Energy = Solver.SolveDAVIDSON( denS, Ltensors, Atensors, Btensors, Ctensors, Dtensors, S0tensors, S1tensors, F0tensors, F1tensors, Qtensors, Xtensors, nStates - 1, VeffTilde );
Energy += Prob->gEconst();
if ( Exc_activated ){ cleanup_excitations( VeffTilde ); }
gettimeofday( &end, NULL );
timings[ CHEMPS2_TIME_S_SOLVE ] += ( end.tv_sec - start.tv_sec ) + 1e-6 * ( end.tv_usec - start.tv_usec );
// Decompose the S-object. MPI_CHEMPS2_MASTER decomposes denS. Each MPI process returns the correct discWeight. Each MPI process has the new MPS tensors set.
gettimeofday( &start, NULL );
if (( noise_level > 0.0 ) && ( am_i_master )){ denS->addNoise( noise_level ); }
const double discWeight = denS->Split( MPS[ index ], MPS[ index + 1 ], virtual_dimension, moving_right, change );
delete denS;
if ( discWeight > MaxDiscWeightLastSweep ){ MaxDiscWeightLastSweep = discWeight; }
gettimeofday( &end, NULL );
timings[ CHEMPS2_TIME_S_SPLIT ] += ( end.tv_sec - start.tv_sec ) + 1e-6 * ( end.tv_usec - start.tv_usec );
return Energy;
}
void CheMPS2::DMRG::calc2DM(){
//First get the whole MPS into left-canonical form
int index = Prob->gL()-2;
Sobject * denS = new Sobject(index,denBK->gIrrep(index),denBK->gIrrep(index+1),denBK);
denS->Join(MPS[index],MPS[index+1]);
Heff Solver(denBK, Prob);
double Energy = 0.0;
double ** VeffTilde = NULL;
if (Exc_activated){
VeffTilde = new double*[nStates-1];
for (int cnt=0; cnt<nStates-1; cnt++){
VeffTilde[cnt] = new double[denS->gKappa2index(denS->gNKappa())];
calcVeffTilde(VeffTilde[cnt], denS, cnt);
}
}
Energy = Solver.SolveDAVIDSON(denS, Ltensors, Atensors, Btensors, Ctensors, Dtensors, S0tensors, S1tensors, F0tensors, F1tensors, Qtensors, Xtensors, nStates-1, VeffTilde);
if (Exc_activated){
for (int cnt=0; cnt<nStates-1; cnt++){ delete [] VeffTilde[cnt]; }
delete [] VeffTilde;
}
Energy += Prob->gEconst();
if (Energy<MinEnergy){ MinEnergy = Energy; }
denS->Split(MPS[index],MPS[index+1],OptScheme->getD(OptScheme->getNInstructions()-1),true,true);
delete denS;
cout << "*********************" << endl;
cout << "** 2DM calculation **" << endl;
cout << "*********************" << endl;
updateMovingRightSafe(index);
TensorDiag * Norm = new TensorDiag(Prob->gL(), denBK);
MPS[Prob->gL()-1]->QR(Norm);
delete Norm;
//Then calculate step by step the 2DM
if (!the2DMallocated){
the2DMallocated = true;
the2DM = new TwoDM(denBK, Prob);
}
for (int siteindex=Prob->gL()-1; siteindex>=0; siteindex--){
the2DM->FillSite(MPS[siteindex], Ltensors, F0tensors, F1tensors, S0tensors, S1tensors);
if (siteindex>0){
TensorDiag * Left = new TensorDiag(siteindex, denBK);
MPS[siteindex]->LQ(Left);
MPS[siteindex-1]->RightMultiply(Left);
delete Left;
updateMovingLeftSafe2DM(siteindex-1);
}
}
//Then perform two checks: double trace & energy
double NtimesNminus1 = the2DM->doubletrace2DMA();
cout << " N(N-1) = " << denBK->gN() * (denBK->gN() - 1) << " and calculated by double trace of the 2DM-A = " << NtimesNminus1 << endl;
double Energy2DMA = the2DM->calcEnergy();
cout << " Energy obtained by Heffective at edge = " << Energy << " and as Econst + 0.5*trace(2DM-A*Ham) = " << Energy2DMA << endl;
}
void CheMPS2::DMRG::solve_fock( const int dmrg_orb1, const int dmrg_orb2, const double alpha, const double beta ){
#ifdef CHEMPS2_MPI_COMPILATION
const bool am_i_master = ( MPIchemps2::mpi_rank() == MPI_CHEMPS2_MASTER );
#else
const bool am_i_master = true;
#endif
if ( dmrg_orb1 == dmrg_orb2 ){
MPS[ dmrg_orb1 ]->number_operator( 2 * alpha, beta ); // alpha * ( E_zz + E_zz ) + beta * 1
return;
}
double sweep_inproduct = 0.0;
if ( dmrg_orb1 + 1 == dmrg_orb2 ){
Sobject * newS = new Sobject( dmrg_orb1, denBK );
if ( am_i_master ){
Sobject * oldS = new Sobject( dmrg_orb1, denBK );
oldS->Join( MPS[ dmrg_orb1 ], MPS[ dmrg_orb2 ] );
sweep_inproduct = Excitation::matvec( denBK, denBK, dmrg_orb1, dmrg_orb2, alpha, alpha, beta, newS, oldS, NULL, NULL, NULL );
delete oldS;
}
// MPI_CHEMPS2_MASTER decomposes newS. Each MPI process returns the correct discarded_weight. Each MPI process has the new MPS tensors set.
const double discarded_weight = newS->Split( MPS[ dmrg_orb1 ], MPS[ dmrg_orb2 ], OptScheme->get_D( OptScheme->get_number() - 1 ), true, true );
delete newS;
}
if ( dmrg_orb1 + 1 < dmrg_orb2 ){
SyBookkeeper * newBK = denBK;
denBK = new SyBookkeeper( *newBK );
newBK->restart( dmrg_orb1 + 1, dmrg_orb2, OptScheme->get_D( OptScheme->get_number() - 1 ) );
TensorT ** old_mps = new TensorT * [ L ];
for ( int orbital = dmrg_orb1; orbital <= dmrg_orb2; orbital++ ){
old_mps[ orbital ] = MPS[ orbital ];
old_mps[ orbital ]->sBK( denBK );
MPS[ orbital ] = new TensorT( orbital, newBK );
MPS[ orbital ]->random();
left_normalize( MPS[ orbital ], NULL ); // MPI_CHEMPS2_MASTER broadcasts MPS[ orbital ] ( left-normalized ).
}
TensorO ** overlaps = NULL;
TensorL ** regular = NULL;
TensorL ** trans = NULL;
if ( am_i_master ){
overlaps = new TensorO*[ L - 1 ];
regular = new TensorL*[ L - 1 ];
trans = new TensorL*[ L - 1 ];
for ( int cnt = 0; cnt < L - 1; cnt++ ){
overlaps[ cnt ] = NULL;
regular[ cnt ] = NULL;
trans[ cnt ] = NULL;
}
for ( int orbital = dmrg_orb1; orbital < dmrg_orb2 - 1; orbital++ ){
solve_fock_update_helper( orbital, dmrg_orb1, dmrg_orb2, true, MPS, old_mps, newBK, denBK, overlaps, regular, trans );
}
}
// Sweeps
bool change = false;
for ( int instruction = 0; instruction < OptScheme->get_number(); instruction++ ){
int num_iterations = 0;
double previous_inproduct = sweep_inproduct + 10 * OptScheme->get_energy_conv( instruction );
while (( fabs( sweep_inproduct - previous_inproduct ) > OptScheme->get_energy_conv( instruction ) ) && ( num_iterations < OptScheme->get_max_sweeps( instruction ) )){
{
const double noise_level = fabs( OptScheme->get_noise_prefactor( instruction ) ) * MaxDiscWeightLastSweep;
MaxDiscWeightLastSweep = 0.0;
for ( int index = dmrg_orb2 - 1; index > dmrg_orb1; index-- ){
Sobject * newS = new Sobject( index, newBK );
if ( am_i_master ){
Sobject * oldS = new Sobject( index, denBK );
oldS->Join( old_mps[ index ], old_mps[ index + 1 ] );
sweep_inproduct = Excitation::matvec( newBK, denBK, dmrg_orb1, dmrg_orb2, alpha, alpha, beta, newS, oldS, overlaps, regular, trans );
delete oldS;
if ( noise_level > 0.0 ){ newS->addNoise( noise_level ); }
}
// MPI_CHEMPS2_MASTER decomposes newS. Each MPI process returns the correct discarded_weight. Each MPI process has the new MPS tensors set.
const double discarded_weight = newS->Split( MPS[ index ], MPS[ index + 1 ], OptScheme->get_D( instruction ), false, change );
if ( discarded_weight > MaxDiscWeightLastSweep ){ MaxDiscWeightLastSweep = discarded_weight; }
delete newS;
if ( am_i_master ){
solve_fock_update_helper( index, dmrg_orb1, dmrg_orb2, false, MPS, old_mps, newBK, denBK, overlaps, regular, trans );
}
}
}
change = true;
{
const double noise_level = fabs( OptScheme->get_noise_prefactor( instruction ) ) * MaxDiscWeightLastSweep;
MaxDiscWeightLastSweep = 0.0;
for ( int index = dmrg_orb1; index < dmrg_orb2 - 1; index++ ){
Sobject * newS = new Sobject( index, newBK );
if ( am_i_master ){
Sobject * oldS = new Sobject( index, denBK );
oldS->Join( old_mps[ index ], old_mps[ index + 1 ] );
sweep_inproduct = Excitation::matvec( newBK, denBK, dmrg_orb1, dmrg_orb2, alpha, alpha, beta, newS, oldS, overlaps, regular, trans );
delete oldS;
if ( noise_level > 0.0 ){ newS->addNoise( noise_level ); }
}
// MPI_CHEMPS2_MASTER decomposes newS. Each MPI process returns the correct discarded_weight. Each MPI process has the new MPS tensors set.
const double discarded_weight = newS->Split( MPS[ index ], MPS[ index + 1 ], OptScheme->get_D( instruction ), true, change );
if ( discarded_weight > MaxDiscWeightLastSweep ){ MaxDiscWeightLastSweep = discarded_weight; }
delete newS;
if ( am_i_master ){
solve_fock_update_helper( index, dmrg_orb1, dmrg_orb2, true, MPS, old_mps, newBK, denBK, overlaps, regular, trans );
}
}
}
#ifdef CHEMPS2_MPI_COMPILATION
CheMPS2::MPIchemps2::broadcast_array_double( &sweep_inproduct, 1, MPI_CHEMPS2_MASTER );
#endif
previous_inproduct = sweep_inproduct;
num_iterations++;
}
}
if ( am_i_master ){
for ( int index = 0; index < L - 1; index++ ){
if ( overlaps[ index ] != NULL ){ delete overlaps[ index ]; }
if ( regular[ index ] != NULL ){ delete regular[ index ]; }
if ( trans[ index ] != NULL ){ delete trans[ index ]; }
}
delete [] overlaps;
delete [] regular;
delete [] trans;
}
for ( int orbital = dmrg_orb1; orbital <= dmrg_orb2; orbital++ ){ delete old_mps[ orbital ]; }
delete [] old_mps;
delete denBK;
denBK = newBK;
}
if ( am_i_master ){
const double rdm_inproduct = 2 * alpha * the2DM->get1RDM_DMRG( dmrg_orb1, dmrg_orb2 ) + beta;
cout << "DMRG::solve_fock : Accuracy = " << fabs( sweep_inproduct / ( Prob->gTwoS() + 1 ) - rdm_inproduct ) << endl;
}
}