(** Electronic kinetic energy integrals, expressed as a matrix in a {Basis.t}.

{%
$$
T_{ij} = \left \langle \chi_i \left| -\frac{1}{2} \Delta \right| \chi_j \right \rangle
$$
%}
*)

type t = Lacaml.D.Mat.t

val of_basis : Basis.t -> t
(** Build from a {Basis.t}. *)

val to_file : filename:string -> t -> unit
(** Write the integrals in a file. *)