Subject: Problems with BSSE in B3LYP H-bond calculations

From: Bosco <[email-masked]>
Date: Mon, 05 Aug 2002 16:21:46 -0300

Dear collegues

        I am calculating the XH---Pyrazine system, with X = F, CN, Cl,
NC and CCH.
        The H-bond energies calculated using the 6-31++G(d,p) basis set
at HF, B3LYP and MP2 levels predict the following order of stability:

        FH > CNH > Cl > NCH > HCCH.

        The procedure of Boys and Bernadi for calculating the BSSE
decreases the H-bond energy when using RHF and MP2 methods. However, for
DFT/B3LYP method, the corrected H-bond energies (i.e., including BSSE)
for the complexes with XH = FH, CNH and ClH are slightly larger than the
corresponding uncorrected values.
        Do you know something similar (reference) or a justification for
that?
        Thanks in advance,

                Bosco

--
Prof. João Bosco Paraiso da Silva

e-mail: [email-masked]
Bosco´s Homepage: www.dqf.ufpe.br/Professores/Bosco/Bosco.html

Departamento de Química Fundamental
Universidade Federal de Pernambuco
50740.250 - Recife (PE) - Brazil

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