(** Two-electron integrals with an arbitrary operator, with a functorial interface            
    parameterized by the fundamental two-electron integrals. 

    {% $(00|00)^m = \int \int \phi_p(r1) \hat{O} \phi_q(r2) dr_1 dr_2 $ %} : Fundamental two-electron integral

*)


module type Zero_mType =
  sig
val name : string
(** Name of the kind of integrals, for printing purposes. *)

val zero_m : Zero_m_parameters.t -> float array
(** The returned float array contains all the {% $(00|00)^m$ %} values, where
    [m] is the index of the array.

    - [maxm] : Maximum total angular momentum
    - [expo_pq_inv] : {% $1/p + 1/q$ %} where {% $p$ %} and {% $q$ %} are the
      exponents of {% $\phi_p$ %} and {% $\phi_q$ %}
    - [norm_pq_sq] : square of the distance between the centers of
      {% $\phi_p$ %} and {% $\phi_q$ %}

*)

  end


module Make : functor (Zero_m : Zero_mType) -> 
    sig
      include module type of FourIdxStorage

      val filter_contracted_shell_pairs :
        ?cutoff:float ->
        ContractedShellPair.t list -> ContractedShellPair.t list
      (** Uses Schwartz screening on contracted shell pairs. *)

      val of_basis : Basis.t -> t
      (** Compute all ERI's for a given {!Basis.t}. *)

    end