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https://gitlab.com/scemama/QCaml.git
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75 lines
2.5 KiB
OCaml
75 lines
2.5 KiB
OCaml
type t =
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{
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elec_num : int;
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mo_basis : MOBasis.t;
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mo_class : MOClass.t;
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spin_determinants : Spindeterminant.t array;
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}
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let spin_determinants t = t.spin_determinants
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let elec_num t = t.elec_num
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let mo_basis t = t.mo_basis
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let mo_class t = t.mo_class
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let size t = Array.length t.spin_determinants
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let fci_of_mo_basis ~frozen_core mo_basis elec_num =
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let mo_num = MOBasis.size mo_basis in
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let mo_class = MOClass.fci ~frozen_core mo_basis in
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let m l =
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List.fold_left (fun accu i -> let j = i-1 in
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Bitstring.logor accu (Bitstring.shift_left_one mo_num j)
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) (Bitstring.zero mo_num) l
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in
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let occ_mask = m (MOClass.core_mos mo_class)
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and active_mask = m (MOClass.active_mos mo_class)
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in
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let neg_active_mask = Bitstring.lognot active_mask in
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(* Here we generate the FCI space and filter out unwanted determinants
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with excitations involving the core electrons. This should be improved. *)
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let spin_determinants =
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Bitstring.permtutations elec_num mo_num
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|> List.filter (fun b -> Bitstring.logand neg_active_mask b = occ_mask)
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|> Array.of_list
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|> Array.map (fun b -> Spindeterminant.of_bitstring b)
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in
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{ elec_num ; mo_basis ; mo_class ; spin_determinants }
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let cas_of_mo_basis mo_basis ~frozen_core elec_num n m =
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let mo_num = MOBasis.size mo_basis in
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let mo_class = MOClass.cas_sd ~frozen_core mo_basis n m in
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let m l =
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List.fold_left (fun accu i -> let j = i-1 in
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Bitstring.logor accu (Bitstring.shift_left_one mo_num j)
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) (Bitstring.zero mo_num) l
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in
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let active_mask = m (MOClass.active_mos mo_class) in
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let occ_mask = m (MOClass.core_mos mo_class) in
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let inactive_mask = m (MOClass.inactive_mos mo_class) in
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let occ_mask = Bitstring.logor occ_mask inactive_mask in
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let neg_active_mask = Bitstring.lognot active_mask in
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(* Here we generate the FCI space and filter out all the unwanted determinants.
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This should be improved. *)
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let spin_determinants =
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Bitstring.permtutations elec_num mo_num
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|> List.filter (fun b -> Bitstring.logand neg_active_mask b = occ_mask)
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|> Array.of_list
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|> Array.map (fun b -> Spindeterminant.of_bitstring b)
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in
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{ elec_num ; mo_basis ; mo_class ; spin_determinants }
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let pp ppf t =
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Format.fprintf ppf "@[<v 2> [";
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let pp = Spindeterminant.pp @@ MOBasis.size (mo_basis t) in
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Array.iteri (fun i d ->
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Format.fprintf ppf "@[<v>@[%8d@] @[%a@]@]@;" i pp d)
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(spin_determinants t) ;
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Format.fprintf ppf "]@]"
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