Bonding and Correlation Analysis of Various SI2CO Isomers on the Potential Energy Surface

摘要

At various levels of theory, singlet and triplet potential energy surfaces (PESs) of Si2CO, 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)/6-311+G(2d)//QCISD/6-311G(2d)+ZPVE level, the global minimum (1)1 (0.0 kcal/mol) corresponds to a three-membered ring singlet O-cCSiSi ((1)A'). On the singlet PES, the species (1)2 (0.2 kcal/mol) is a bent SiCSiO structure with a (1)A' electronic state, followed by a three-membered ring isomer Si-cCSiO ((1)A') (1)3 (23.1 kcal/mol) and a linear SiCOSi (1)4 ((1)Sigma(+)) (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 (B-3(2)) (18.8 kcal/mol) and (3)7 ((3)A '') (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 C3O, C3S, SiC2O, and SiC2S are discussed. The present results are also expected to be useful for understanding the initial growing step of the CO-doped Si vaporization processes. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109: 907-919,2009