type t = {
  charge            : Charge.t;
  electrons         : Electrons.t ;
  nuclei            : Nuclei.t;
  basis             : Basis.t;
  ao_basis          : AOBasis.t;
  nuclear_repulsion : float;
}

let make ?cartesian:(cartesian=false)
         ?multiplicity:(multiplicity=1)
         ?charge:(charge=0)
         ~nuclei
         basis
  =

  (* Tune Garbage Collector *)
  let gc = Gc.get () in
  Gc.set { gc with space_overhead = 1000  };

  let electrons =
    Electrons.make ~multiplicity ~charge nuclei
  in

  let charge = 
    Charge.(Nuclei.charge nuclei + Electrons.charge electrons)
  in

  let ao_basis = 
    AOBasis.make ~basis ~cartesian nuclei
  in

  let nuclear_repulsion = 
    Nuclei.repulsion nuclei
  in

  {
    charge ; basis ; nuclei ; electrons ; ao_basis ;
    nuclear_repulsion ; 
  }


let of_filenames ?cartesian:(cartesian=false) ?multiplicity:(multiplicity=1) ?charge:(charge=0) ~nuclei basis_filename =
  let nuclei =
    Nuclei.of_filename nuclei
  in
  let basis =
    Basis.of_nuclei_and_basis_filename ~nuclei basis_filename
  in
  lazy (make ~cartesian ~charge ~multiplicity ~nuclei basis)
  |> Parallel.broadcast