subroutine hcore_guess
  BEGIN_DOC
! Produce `H_core` MO orbital
  END_DOC
  implicit none
  character*(64)                 :: label
  label = 'Guess'
  call mo_as_eigvectors_of_mo_matrix(mo_one_e_integrals,          &
                                     size(mo_one_e_integrals,1),  &
                                     size(mo_one_e_integrals,2),label,1,.true.)
  call nullify_small_elements(ao_num, mo_num, mo_coef, size(mo_coef,1), 1.d-12 )
  call save_mos
  TOUCH mo_coef mo_label
end