Periodic Hartree-Fock study of minerals: Tetracoordinated silica polymorphs

✍ Scribed by B. Silvi; Ph. D'Arco; V. R. Saunders; R. Dovesi

• Book ID: 104661574
• Publisher: Springer-Verlag
• Year: 1991
• Tongue: English
• Weight: 742 KB
• Volume: 17
• Category: Article
• ISSN: 0342-1791
• DOI: 10.1007/bf00202237

✦ Synopsis

Periodic Hartree-Fock STO-3G calculations have been performed on several tetracoordinated silica polymorphs: low and high quartz, low and idealized high cristobalite and prototype tridymite. The optimized structural parameters are in overall good agreement with experimental data. In the particular case of e-quartz, the SiO4 tetrahedra are found to be irregular. The optimized values of the two different SiO bond lengths are respectively 1.608 ~ and 1.613/~. The potential energy versus tilt angle curves suggest a picture of the high temperature phases in terms of delocalized oxygen atoms which is consistent with a disordered structure. Finally, the bonding in silica polymorphs is discussed from electron density maps and Mulliken population analysis.