mirror of https://gitlab.com/scemama/QCaml.git
65 lines
1.7 KiB
OCaml
65 lines
1.7 KiB
OCaml
(** Long-range electron-electron repulsion integrals.
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See Eq(52) in 10.1039/b605188j
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*)
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open Constants
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open Util
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module Csp = ContractedShellPair
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module Cspc = ContractedShellPairCouple
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module T = struct
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let name = "Long-range electron repulsion integrals"
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open Zero_m_parameters
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let zero_m z =
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let mu_erf =
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match z.range_separation with
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| Some x -> x
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| None -> 0.5 (* TODO invalid_arg "range_separation is None" *)
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in
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let m = mu_erf *. mu_erf in
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let expo_pq_inv = z.expo_p_inv +. z.expo_q_inv in
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let fG_inv = expo_pq_inv +. 1. /. m in
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let fG = 1. /. fG_inv in
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assert (expo_pq_inv <> 0.);
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let t =
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if z.norm_pq_sq > integrals_cutoff then
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z.norm_pq_sq *. fG
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else 0.
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in
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let maxm = z.maxm in
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let result = boys_function ~maxm t in
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let rec aux accu k = function
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| 0 -> result.(k) <- result.(k) *. accu
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| l ->
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begin
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result.(k) <- result.(k) *. accu;
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let new_accu = -. accu *. fG in
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(aux [@tailcall]) new_accu (k+1) (l-1)
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end
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in
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let f = two_over_sq_pi *. (sqrt fG) in
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aux f 0 maxm;
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result
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let class_of_contracted_shell_pair_couple shell_pair_couple =
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let shell_p = Cspc.shell_pair_p shell_pair_couple
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and shell_q = Cspc.shell_pair_q shell_pair_couple
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in
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if Array.length (Csp.shell_pairs shell_p) +
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(Array.length (Csp.shell_pairs shell_q)) < 4 then
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TwoElectronRR.contracted_class_shell_pair_couple
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~zero_m shell_pair_couple
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else
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TwoElectronRRVectorized.contracted_class_shell_pairs
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~zero_m shell_p shell_q
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end
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module M = TwoElectronIntegrals.Make(T)
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include M
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