Accurate ab initio anharmonic force field and heat of formation for silane

From large basis set coupled cluster calculations and a minor empirical adjustment, an anharmonic force field for silane has been derived that is consistently of spectroscopic quality (+/-1 cm(-1) on vibrational fundamentals) for all isotopomers of silane studied. Inner-shell polarization functions have an appreciable effect on computed properties and even on anharmonic corrections. From large basis set coupled cluster calculations and extrapolations to the infinite-basis set limit, we obtain TAE(0) = 303.80 +/- 0.18 kcal mol(-1), which includes an anharmonic zero-point energy (19.59 kcal mol(-1)), inner-shell correlation (-0.36 kcal mol(-1)), scalar relativistic corrections (-0.70 kcal mol(-1)) and atomic spin-orbit corrections (-0.43 kcal mol(-1)). In combination with the recently revised Delta H<((f))over circle>,(0)[Si(g)], we obtain Delta H<((f))over circle>,(0)[SiH4(g)] = 9.9 +/- 0.4 kcal mol(-1) in between the two established experimental values.