openfermion.linalg.Davidson

Davidson algorithm to get the n states with smallest eigenvalues.

Methods

get_lowest_n

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Returns n smallest eigenvalues and corresponding eigenvectors for linear_operator.

Args
n(int): The number of states corresponding to the smallest eigenvalues and associated eigenvectors for the linear_operator. initial_guess(numpy.ndarray[complex]): Initial guess of eigenvectors associated with the n smallest eigenvalues. max_iterations(int): Max number of iterations when not converging.

Returns
success(bool): Indicates whether it converged, i.e. max elementwise error is smaller than eps. eigen_values(numpy.ndarray[complex]): The smallest n eigenvalues. eigen_vectors(numpy.ndarray[complex]): The smallest n eigenvectors corresponding with those eigen values.