openfermion.linalg.Davidson

Davidson algorithm to get the n states with smallest eigenvalues.

openfermion.linalg.Davidson(
    linear_operator, linear_operator_diagonal, options=None
)

Methods

get_lowest_n

View source

get_lowest_n(
    n_lowest=1, initial_guess=None, max_iterations=None
)

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.