eigenΒΆ

The eigenvalues and eigenvectors of the Hamiltonian obtained by the UHF method are exported in npz (numpy zip archive) format.

The filename is chosen, with the string specified for the eigen keyword in file.output section (indicated by eigen_str hereafter), as {key}_eigen_str.npz, where {key} turns to be:

  • sz-free if the parameter 2Sz is not specified in mode.param section,

  • spin-up and spin-down otherwise. (yields two files)

The code shown below is an example for reading data from the file using Python.

import numpy as np
data = np.load("key_eigen_str.npz")
eigenvalue = data["eigenvalue"]
eigenvector = data["eigenvector"]

eigenvalue holds a list of eigenvalues in ascending order. The number of eigenvalues is N if 2Sz is specified, or 2N otherwise, for N being the total number of sites.

eigenvector holds the corresponding eigenvectors as a two-dimensional array: The first index refers to the site index i_site and the spin index s_spin (0 for up-spin, and 1 for down-spin) by:

  • i_site if 2Sz is specified, or

  • i_site + s_spin * N otherwise.

The second index refers to the index of the eigenvalues.