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95 lines
2.8 KiB
OCaml
95 lines
2.8 KiB
OCaml
(**
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A spin-determinant is one of the two determinants in the Waller-Hartree
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double determinant representation of a Slater determinant. It is represented
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as a bit string and a phase factor.
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*)
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type t
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type hole = int
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type particle = int
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(** {1 Accessors}. *)
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val phase : t -> Phase.t
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(** Phase factor.
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@raise Invalid_argument if the spin-determinant is [None].
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*)
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val set_phase : Phase.t -> t -> t
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(** Returns a spin-determinant with the phase set to [p]. *)
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val bitstring : t -> Bitstring.t
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(** Bit string.
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@raise Invalid_argument if the spin-determinant is [None].
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*)
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val is_none : t -> bool
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(** Tests if a spin-determinant is [None]. *)
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val negate_phase : t -> t
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(** Returns a spin-determinant with the phase reversed. *)
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(** {1 Second quantization operators} *)
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val vac : int -> t
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(** Vacuum state, [vac = Some ]{% $|\rangle$ %}. The integer parameter contains the
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number of orbitals in the basis set. *)
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val creation : particle -> t -> t
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(** [creation p] is the creation operator {% $a^\dagger_p$ %}. *)
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val annihilation : hole -> t -> t
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(** [annihilation h] is the annihilation operator {% $a_h$ %}. *)
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val single_excitation : hole -> particle -> t -> t
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(** Single excitation operator {% $T_h^p = a^\dagger_p a_h$ %}. *)
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val double_excitation : hole -> particle -> hole -> particle -> t -> t
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(** Double excitation operator {% $T_{hh'}^{pp'} = a^\dagger_p a^\dagger_{p'} a_{h'} a_h$ %}. *)
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val degree : t -> t -> int
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(** Returns degree of excitation between two spin-determinants. *)
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val holes_of : t -> t -> int list
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(** Returns the list of holes in the excitation from one determinant to another. *)
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val particles_of : t -> t -> int list
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(** Returns the list of particles in the excitation from one determinant to another. *)
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val holes_particles_of : t -> t -> (int*int) list
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(** Returns the list of pairs of holes/particles in the excitation from one determinant to
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another. *)
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val n_electrons : t -> int
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(** Returns the number of electrons in the determinant. *)
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(** {1 Creation} *)
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val of_bitstring : ?phase:Phase.t -> Bitstring.t -> t
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(** Creates from a bitstring and an optional phase.*)
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val of_list : int -> int list -> t
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(** Builds a spin-determinant from a list of orbital indices. If the creation of the
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spin-determinant is not possible because of Pauli's exclusion principle, a [None]
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spin-determinant is returned.
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The first integer is the size of the MO basis set. *)
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val to_list : t -> int list
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(** Transforms a spin-determinant into a list of orbital indices. *)
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val to_array : t -> int array
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(** Transforms a spin-determinant into an array of orbital indices. *)
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(** {1 Printers}. *)
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val pp : int -> Format.formatter -> t -> unit
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(** First [int] is the number of MOs to print *)
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(** {1 Unit testing} *)
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val test_case : unit -> (string * [> `Quick ] * (unit -> unit)) list
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