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

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 H f 0[Si(g)], we obtain H f ;0[SiH4(g)] = 9:9 0:4 kcal mol- 1 in between the two established experimental values.