Anharmonic effects in the infra-red spectrum of SiH3Br — an ab initio study

The potential energy surface of SiH3Br was calculated up to quartic terms by ab initio quantum chemistry. To obtain the harmonic force field we performed a MP2 calculation with a large (TZ2P) basis set, while the cubic and quartic components have been evaluated both at SCF and MP2 levels. Second-order perturbation theory was then used to evaluate many of the constants describing anharmonicity of the molecular potential. The Coriolis resonance between the modes ν2 and ν5 was accounted for. A comparison with experimental data confirms ohe quality of our calculation.