Bonding and correlation analysis of various Si₂CO isomers on the potential energy surface

Abstract

ABSTRACT:At various levels of theory, singlet and triplet potential energy surfaces (PESs) of Si 2 CO, which has been studied using matrix isolation infrared spectroscopy, are investigated in detail. A total of 30 isomers and 38 interconversion transition states are obtained at the B3LYP/6-311G(d) level. At the higher CCSD(T)/6-311ϩG(2d)// QCISD/6-311G(2d)ϩZPVE level, the global minimum 1 1 (0.0 kcal/mol) corresponds to a three-membered ring singlet O-cCSiSi ( 1 AЈ). On the singlet PES, the species 1 2 (0.2 kcal/ mol) is a bent SiCSiO structure with a 1 AЈ electronic state, followed by a threemembered ring isomer Si-cCSiO ( 1 AЈ) 1 3 (23.1 kcal/mol) and a linear SiCOSi 1 4 ( 1 ⌺ ϩ ) (38.6 kcal/mol). The isomers 1 1, 1 2, 1 3, and 1 4 possess not only high thermodynamic stabilities, but also high kinetic stabilities. On the triplet PES, two isomers 3 1 ( 3 B 2 ) (18.8 kcal/mol) and 3 7 ( 3 AЉ) (23.3 kcal/mol) also have high thermodynamic and kinetic stabilities. The bonding natures of the relevant species are analyzed. The similarities and differences between C 3 O, C 3 S, SiC 2 O, and SiC 2 S are discussed. The present results are also expected to be useful for understanding the initial growing step of the COdoped Si vaporization processes.