Spectroscopic parameters of SiC4

Structural and anharmonic spectroscopic properties of SiC4 are investigated using the RCCSD(T)-F12 method and second order perturbation theory. Observable parameters are determined for various isotopomers, 28Si12C4, 28Si13CCCC, 28SiC13CCC, 28SiCC 13CC, 28SiCCC 13C and 29SiC4. Fermi interactions are considered in the model. Results are compared with the parameters of C5. Si12C4, the ν1 fundamental has been found at 2094 cm−1 with RCCSD(T)-F12, close to the observed value 2095.46 cm−1. In addition, B0 has been determined to be 1536.29 MHz with RCCSD(T)/CBS, whereas the experimental value is 1533.8 MHz. The CASSCF/aug-cc-pVTZ equilibrium dipole moment was estimated to be 6.2112 Debyes.