Open AccessSystematic Theoretical Study of Non-nuclear Electron Density Maxima in Some Diatomic Molecules
Author(s) -
Luiz Alberto Terrabuio,
Tiago Quevedo Teodoro,
M. G. Rachid,
Roberto Luiz Andrade Haiduke
Publication year - 2013
Publication title -
the journal of physical chemistry. a/the journal of physical chemistry. a.
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 235
eISSN - 1520-5215
pISSN - 1089-5639
DOI - 10.1021/jp406992q
Subject(s) - homonuclear molecule , diatomic molecule , maxima , chemistry , bond length , atomic physics , dipole , heteronuclear molecule , electronic correlation , molecular physics , basis (linear algebra) , valence electron , quadrupole , electron , molecule , physics , quantum mechanics , geometry , art , organic chemistry , performance art , art history , mathematics
First, exploratory calculations were performed to investigate the presence of non-nuclear maxima (NNMs) in ground-state electron densities of homonuclear diatomic molecules from hydrogen up to calcium at their equilibrium geometries. In a second stage, only for the cases in which these features were previously detected, a rigorous analysis was carried out by several combinations of theoretical methods and basis sets in order to ensure that they are not only calculation artifacts. Our best results support that Li2, B2, C2, and P2 are molecules that possess true NNMs. A NNM was found in values obtained from the largest basis sets for Na2, but it disappeared at the experimental geometry because optimized bond lengths are significantly inaccurate for this case (deviations of 0.10 Å). Two of these maxima are also observed in Si2 with CCSD and large basis sets, but they are no longer detected as core-valence correlation or multiconfigurational wave functions are taken into account. Therefore, the NNMs in Si2 can be considered unphysical features due to an incomplete treatment of electron correlation. Finally, we show that a NNM is encountered in LiNa, representing the first discovery of such electron density maxima in a heteronuclear diatomic system at its equilibrium geometry, to our knowledge. Some results for LiNa, found in variations in internuclear distances, suggest that molecular electric moments, such as dipole and quadrupole, are sensitive to the presence of NNMs.