ueg_sign_problem

Script to investigate the sign problem in a UEG system in various bases.

Execute to calculate and print out the lowest eigenvalues of Hamiltonian matrices (and those related to the FCIQMC sign problem) for a small UEG system using the ueg_fci module.

ueg_sign_problem.print_title(title, under='=')

Print the underlined title.

Parameters:
  • title (string) – section title to print out
  • under (string) – single character used to underline the title
ueg_sign_problem.worker(label, sys, basis, Hamil, nprint)

Helper function to construct and diagonalise matrices related to the sign problem.

Parameters:
  • label (string) – label of the many-particle basis function used
  • sys (ueg_fci.UEG) – desired UEG system; passed to Hamil
  • basis (iterable of iterables of ueg_fci.BasisFn) – set of many-particle basis functions
  • Hamil (ueg_fci.UEGHamiltonian subclass) – appropriate Hamiltonian for the basis provided
  • nprint (integer) – number of eigenvalues to print out