Theoretical study of the heats of formation of small silicon-containing compounds

Journal Article · Thu Aug 12 04:00:00 EDT 1999 · Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory

DOI:https://doi.org/10.1021/jp990596g· OSTI ID:20000060

Feller, D; Dixon, D A

Heats of formation for nine small silicon-containing molecules were obtained from large basis set ab initio calculations using coupled cluster theory with a perturbative treatment of triple excitations. After adjusting the atomization energies for the finite basis set truncation error, core/valence correlation, scalar relativistic, higher order correlation, and atomic spin-orbit effects, the theoretical and experimental 0 K values of {Delta}H{sub f} values were in good agreement. Using 106.6 kcal/mol as the heat of formation of silicon, the authors obtain {Delta}H{sub f} values of SiH = 87.7 {+-} 0.4 vs 89.5 {+-} 0.7 (expt); SiH{sub 2}({sup 1}A{sub 1}) = 64.1 {+-} 0.4 vs 65.5 {+-} 0.7 (expt); SiH{sub 2}({sup 3}B{sub 1}{minus})= 85.4 {+-} 0.4 vs 86.5 {+-} 0.7 (expt); SiH{sub 3} = 47.3 {+-} 0.5 vs 47.7 {+-} 1.2 (expt); SiH{sub 4} = 8.7 {+-} 0.6 vs 9.5 {+-} 0.5 (expt); Si{sub 2} = 138.8 {+-} 0.4 vs 139.2 (expt); Si{sub 2}H{sub 6} = 19.7 {+-} 0.5 vs 20.9 {+-} 0.3 (expt); SiF = {minus}14.8 {+-} 0.4 vs {minus}5.2 {+-} 3 (expt); SiF{sub 2} = {minus}151.7 {+-} 0.5 vs {minus}140.3 {+-} 3 (expt); and SiF{sub 4} = {minus}384.5 {+-} 0.9 vs {minus}384.9 {+-} 0.2 (expt). Based on the present work, the authors suggest a number of revisions in the interpretation of the experimental data. Although a revision in {Delta}H{sub f}{degree}(Si) to 107.4 {+-} 0.6 kcal/mol at 0 K leads to improved agreement between theory and experiment for the SI{sub x}H{sub y} compounds, it worsens agreement for SiF{sub 4}. Given the remaining uncertainties in the theoretical approach, more definitive conclusions do not appear to be warranted.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US)
• Sponsoring Organization: US Department of Energy
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 20000060
• Journal Information: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 32 Vol. 103; ISSN 1089-5639; ISSN JPCAFH
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
FORMATION HEAT
SILANES
SILICON FLUORIDES
THEORETICAL DATA
THERMODYNAMIC PROPERTIES