2018-03-27 19:32:37 +02:00
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(** Storage for four-index data (integrals, density matrices, ...).
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There are two kinds of ordering of indices:
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2018-03-28 01:50:19 +02:00
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- Physicist's : {% $\langle i j | k l \rangle$ %}
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- Chemist's : {% $(ij|kl)$ %}
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2018-03-27 19:32:37 +02:00
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*)
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type t
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val create : size:int -> [< `Dense | `Sparse ] -> t
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(** If [`Dense] is chosen, internally the data is stored as a 4-dimensional
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[Bigarray]. Else, it is stored as a hash table.
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*)
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(** {2 Accessors} *)
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val get_chem : t -> int -> int -> int -> int -> float
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val get_phys : t -> int -> int -> int -> int -> float
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val set_chem : t -> int -> int -> int -> int -> float -> unit
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val set_phys : t -> int -> int -> int -> int -> float -> unit
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(** {2 I/O} *)
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val to_file : ?cutoff:float -> filename:string -> t -> unit
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(** Write the data to file, using the physicist's ordering. *)
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