High-level ab initio calculations with large basis sets are reported for si
lene, H2C = SiH2. Correlated harmonic force fields are obtained from couple
d cluster CCSD(T) calculations with the cc-pVQZ basis (cc-pVTZ for H) while
the anharmonic force fields are computed at the MP2/TZ2Pf level. There is
excellent agreement with the available experimental data, in particular the
equilibrium geometry and the fundamental vibrational frequencies. Many oth
er spectroscopic constants are predicted for the C-2v isotopomers of silene
.