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Direct and Indirect Effects of Dispersion Interactions on the Electric Properties of Weakly Bound Complexes
journal contribution
posted on 2015-03-26, 00:00 authored by Miroslav Medveď, Šimon Budzák, Adèle D. Laurent, Denis JacqueminDirect
(electronic) and indirect (geometrical) modifications of
the molecular properties of weakly interacting complexes between the
push–pull p-aminobenzoic acid (pABA) molecule
and the nonpolar benzene (Bz) have been studied with a large panel
of wave function (WF) and density functional theory (DFT) based methods
using carefully selected atomic basis sets. For pABA, both the canonical
(pABA-c) and zwitterionic (pABA-z) forms have been investigated. Owing
to strongly distinct charge distributions, the two forms of pABA enable
us to mimic different interaction modes with Bz. In this work, we
assessed the performances of dispersion-corrected DFT methods, as
well as of long-range corrected exchange–correlation functionals.
It follows from the SAPT analysis that both the structure and the
interaction energy of the first complex (pABA-c···Bz)
is mainly controlled by dispersion interactions whereas, in the second
complex (pABA-z···Bz), electrostatic and induction
forces play also an important role. Our results suggest that the (non)linear
electric properties of push–pull and zwitterionic molecules
can be significantly reduced by the presence of a nonpolar compound.
We also show that even for a complex with stability strongly determined
by dispersion forces, the direct dispersion contributions to its electric
properties can be small. Nevertheless, the intersystem distance is
influenced by dispersion forces, which, in turn indirectly tune the
induced properties. The zwitterionic derivative appears to be more
challenging in the context of molecular properties.