determinants
  N_int         integer
  bit_kind      integer
  n_dets        integer
  n_states      integer
  psi_coef      double precision (determinants_n_dets,determinants_n_states)
  psi_det       integer (determinants_N_int*determinants_bit_kind/4,2,determinants_n_dets)
  H_apply_threshold  double precision