CCL:G: Tozer's diagnostic test in Gaussian

Might the sum be zero because all the converged DFT MO's are orthogonal? It seems like this orthogonality condition is just what you computed.

John McKelvey

On Tue, Jul 15, 2014 at 10:09 AM, J. Phoenix himphoenixCCLa/ <owner-chemistry(!)> wrote:

Sent to CCL by: "J. ÂPhoenix" []
Dear CCLs,

I am trying to compute the Tozer's lambda parameter that relates the spatial overlap between orbitals in a certain excitation using TDDFT calculations (JCP, 128, 044118 (2008)). The procedure I am following is to extract the overlap matrix of AOs in the Gaussian output and then compute for each MO pair: <Psi_1|Psi_2> = sum_i sum_j c_1_i c_2_j <X_i|X_j>, using the MO coefficients. When coefficients are taken with their sign, I get an overlap of one between the same MO, and zero between different MOs. However, when I use the absolute value of the coefficients to compute the inner product of the moduli, overlaps larger than 1 are obtained in some cases.

Is there anything wrong in my procedure for computing the inner product of the moduli of two orbitals or is not expected to be a value between 0 and 1?

Thanks in advance,

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John McKelvey
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