nI_invariant_S2_expval_exc_Excite_2_t Function

private pure function nI_invariant_S2_expval_exc_Excite_2_t(exc) result(res)

Evaluates $< D_i | S^2 | a^\dagger_A a^\dagger_B a_I a_J D_i > = 0$

Arguments

Type	Intent	Optional	Attributes		Name
type(Excite_2_t),	intent(in)			::	exc

Return Value real(kind=dp)

The matrix element. It is real even for complex NECI.

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