Accurateab initioanharmonic force field and heat of formation for silane

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Abstract
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 TAE0 = 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 ΔH o f, o[Si(g)], we obtain ΔH o f.o[SiH4(g)] = 9.9 ± 0.4 kcal mol−1 in between the two established experimental values.