arXiv:physics/9906037v1 [physics.chem-ph] 21 Jun 1999 Accurate ab initio anharmonic force field and heat of formation for silane Jan M.L. Martin ∗ and Kim K. Baldridge † Department of Organic Chemistry, Kimmelman Building, Room 262, Weizmann Institute of Science, 76100 Reh . ovot, Israel. Timothy J. Lee MS230-3, NASA Ames Research Center, Moffett Field, CA 94035-1000, USA (Molecular Physics: received April 19, 1999; accepted June 10, 1999) Abstract From large basis set coupled cluster calculations and a minor empirical ad- justment, an anharmonic force field for silane has been derived that is con- sistently 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 correc- tions. 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, which includes an anharmonic zero-point energy (19.59 kcal/mol), inner-shell corre- lation (-0.36 kcal/mol), scalar relativistic corrections (-0.70 kcal/mol), and atomic spin-orbit corrections (-0.43 kcal/mol). In combination with the re- cently revised ΔH ◦ f,0 [Si(g)], we obtain ΔH ◦ f,0 [SiH 4 (g)]=9.9±0.4 kcal/mol, in ∗ Corresponding author. Email: comartin@wicc.weizmann.ac.il † Permanent address: San Diego Supercomputer Center MC0505, University of California, San Diego, 9500 Gilman Drive, Building 109, La Jolla, CA 92093-0505, USA 1