type t =
{
  elec_num : int;
  mo_basis : MOBasis.t;
  spindets : Spindeterminant.t array;
}

let fci_of_mo_basis mo_basis elec_num =
  let mo_num = MOBasis.size mo_basis in
  let spindets = 
    Util.bit_permtutations elec_num mo_num 
    |> List.map (fun b -> Spindeterminant.of_bitstring b)
    |> Array.of_list
  in
  { elec_num ; mo_basis ; spindets }


let pp_spindet_space ppf t =
  Format.fprintf ppf "@[<v>[";
  Array.iteri (fun i d -> Format.fprintf ppf "@[<h>@[%d@]@;@[%a@]@]@," i Spindeterminant.pp_spindet d) t.spindets;
  Format.fprintf ppf "]@]"