tiny_dmrg/densityMatrix.h at master · iglpdc/tiny_dmrg · GitHub

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/**
 * @file densityMatrix.h
 *
 * @brief Interface for the routines related to the calculation of the
 * reduced density matrix
 *
 * @author Roger Melko
 * @author Ivan Gonzalez
 * @date $Date$
 *
 * $Revision$
 */
#ifndef DENSITY_MATRIX_H
#define DENSITY_MATRIX_H

#include "blitz/array.h"

blitz::Array<double,2> transformOperator(const blitz::Array<double,2>& op,
	const blitz::Array<double,2>& transposed_transformation_matrix,
	const blitz::Array<double,2>& transformation_matrix);

blitz::Array<double,2> calculateReducedDensityMatrix(blitz::Array<double,2> psi);

blitz::Array<double,2> truncateReducedDM(blitz::Array<double,2>& density_matrix,
	const int mm);

void diagonalizeDensityMatrix(blitz::Array<double,2>&
	density_matrix, blitz::Array<double,1>& density_matrix_eigenvalues);

blitz::Array<int,1> orderDensityMatrixEigenvalues(
	blitz::Array<double,1>& density_matrix_eigenvalues);

double calculateTruncationError(
	const blitz::Array<double,1>& density_matrix_eigenvalues,
	const blitz::Array<int,1>& indexes, int m);

#endif //DENSITY_MATRIX_H