S2_expval_exc_Excite_2_t Function

private pure function S2_expval_exc_Excite_2_t(nI, 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
integer,	intent(in)			::	nI(:)	The bra Slater determinant in nI format.
type(Excite_2_t),	intent(in)			::	exc

Return Value real(kind=dp)

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

Contents