A theoretical study of bond energies in model Si-H-Cl molecules using density functional approaches for representing Si surface chemistry
✍ Scribed by Boehm, Randall C.; Kress, Joel D.; Martin, Richard L.; Hay, P. Jeffrey
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 180 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0192-8651
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✦ Synopsis
The reliability of density functional theory DFT methods for calculating Si-H, Si-Cl, and Si-Si bond energies is examined in reactions involving molecules and small clusters representing various surface sites appropriate for Si surface chemistry. Results are presented for systematic studies using a valence double-zeta polarization basis for both all-electron calculations Ž . and valence᎐electron calculations employing effective core potentials ECPs . All-electron DFT results are comparable to much more demanding MP4, G2, and MC᎐SCF᎐CI calculations for computed bond energies. Whereas the use of ECPs introduces systematic energy differences of ca. 3᎐5 kcalrmol compared to AE results, depending on the type of bond involved, the use of ECPs for carrying out calculations on larger clusters is discussed where AE calculations become more computationally demanding. The convergence of Si bond energies as a function of replacing hydrogens with silyl groups is examined. In constructing models to describe etching processes involving Cl species on Si surfaces, the need for incorporating differences in thermochemistries for one-, two-, and three-coordinate Si surface sites is emphasized. Comparisons of semiempirical approaches for thermochemistries of Si-containing species find