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Alex Granovsky
gran@classic.chem.msu.su

Could you please provide some more details - your notation
means that the geometry of, say, A is optimized using combined
basis set; however the question is where the basis functions of
B reside, and whether they are allowed to move as well?
In any case, I'm very skeptical here as the most optimal
geometry corresponds to the "quasi-collapse" of basis
functions of different fragments. However, it is possible
to do this with Firefly... although the details depend on
what exactly you want to do.

Regards,
Alex

P.S. You can use HTML formatting tags including < sub > and < sup > ones.


On Tue Nov 10 '09 2:11pm, Vyacheslav wrote
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>Hi,
>in literature there are two variants of BSSE calculation on Boys-Bernardi's method (CP method) for AB particle consisting of A and B fragments. The first variant is widespread (sorry, for the lack of sub- and superscripts i should fabricate own system of designations):

>ΔE(AB) = E[(AB/αβ)(AB)] – E[(AB/αβ)(A)] – E[(AB/αβ)(B)]        (1)

>In first round brackets, there are geometry / basis set. In second round brackets, the type of a particle is indicated. Components of this equation are easily calculated in Firefly.

>Another variant:

>ΔE(AB) = E[(AB/αβ)(AB)] – E[(A/αβ)(A)] – E[(B/αβ)(B)]        (2)

>It is used, for example, by the Sorgo J.A. in his papers (Theor. Chem. Acc. (1998) 99, 68;  J. Mol. Liq. (Theochem) (2001) 537, 245).
>It would be interesting to compare both variants of BSSE calculation but i do not understand how to calculate the second and third terms of the eq. (2) in Firefly. Here A and B fragments are in its own geometries, but in common basis set (αβ basis is basis set of AB particle).
>Please advise to me something.
>Thanks in advance.
>

[ This message was edited on Sat Nov 14 '09 at 1:00pm by the author ]