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QCaml/perturbation/lib/mp2.ml
2020-12-07 13:52:56 +01:00

63 lines
1.9 KiB
OCaml

open Linear_algebra
type t = float
let make ~frozen_core hf =
let mo_basis =
Mo.Basis.of_hartree_fock hf
in
let epsilon =
Mo.Basis.mo_energies mo_basis
in
let mo_class =
Mo.Class.cas_sd mo_basis ~frozen_core 0 0
|> Mo.Class.to_list
in
let eri =
Mo.Basis.ee_ints mo_basis
in
let inactives =
List.filter (fun i ->
match i with Mo.Class.Inactive _ -> true | _ -> false) mo_class
and virtuals =
List.filter (fun i ->
match i with Mo.Class.Virtual _ -> true | _ -> false) mo_class
in
let rmp2 () =
List.fold_left (fun accu b ->
match b with Mo.Class.Virtual b ->
let eps = -. (epsilon%.(b)) in
accu +.
List.fold_left (fun accu a ->
match a with Mo.Class.Virtual a ->
let eps = eps -. (epsilon%.(a)) in
accu +.
List.fold_left (fun accu j ->
match j with Mo.Class.Inactive j ->
let eps = eps +. epsilon%.(j) in
accu +.
List.fold_left (fun accu i ->
match i with Mo.Class.Inactive i ->
let eps = eps +. epsilon%.(i) in
let ijab = Four_idx_storage.get_phys eri i j a b
and abji = Four_idx_storage.get_phys eri a b j i in
let abij = ijab in
accu +. ijab *. ( abij +. abij -. abji) /. eps
| _ -> accu
) 0. inactives
| _ -> accu
) 0. inactives
| _ -> accu
) 0. virtuals
| _ -> accu
) 0. virtuals
in
match Mo.Hartree_fock.kind hf with
| Mo.Hartree_fock.RHF -> rmp2 ()
| _ -> failwith "Not implemented"