QCaml/CI/Spindeterminant_space.ml

type t =
  {
    elec_num          : int;
    mo_basis          : MOBasis.t;
    mo_class          : MOClass.t;
    spin_determinants : Spindeterminant.t array;
  }


let spin_determinants t = t.spin_determinants
let elec_num t = t.elec_num
let mo_basis t = t.mo_basis
let mo_class t = t.mo_class
let size     t = Array.length t.spin_determinants

let fci_of_mo_basis ?(frozen_core=true) mo_basis elec_num =
  let mo_num = MOBasis.size mo_basis in
  let mo_class = MOClass.fci ~frozen_core mo_basis in
  let m l = 
    List.fold_left (fun accu i -> let j = i-1 in Z.(logor accu (shift_left one j)) 
                   ) Z.zero l
  in
  let occ_mask    = m (MOClass.core_mos    mo_class)
  and active_mask = m (MOClass.active_mos  mo_class)
  in
  let neg_active_mask = Z.lognot active_mask in
  let spin_determinants = 
    Util.bit_permtutations elec_num mo_num 
    |> List.filter (fun b -> Z.logand neg_active_mask b = occ_mask)
    |> List.map (fun b -> Spindeterminant.of_bitstring b)
    |> Array.of_list
  in
  { elec_num ; mo_basis ; mo_class ; spin_determinants }


let pp_spindet_space ppf t =
  Format.fprintf ppf "@[<v 2>[ ";
  Array.iteri (fun i d -> Format.fprintf ppf "@[<v>@[%8d@] @[%a@]@]@;" i
                  (Spindeterminant.pp_spindet (MOBasis.size (mo_basis t))) d) (spin_determinants t) ;
  Format.fprintf ppf "]@]"