A theoretical investigation of the silicon-carbon chain molecule SiC8

Large-scale coupled cluster calculations have been carried out for linear S iC8, a molecule of interest to astrochemistry. An accurate equilibrium stru cture has been established and a large equilibrium dipole moment of mu(e) = -9.96 D is predicted, where the positive end of the dipole is located at t he silicon site. Most promising for future detection by infrared spectrosco py are the stretching vibrations at 1973 and 2103 cm(-1) with absolute inte nsities of 6662 and 3699 km mol(-1), respectively. The lowest bending vibra tion has a harmonic wavenumber of 38 cm(-1). The collinear fragmentation pr ocess SiC8 --> SiC6 + C-2 has been investigated and the corresponding disso ciation energy is predicted to be D-0 = 568 kJ mol(-1).