A computational investigation of 17O quadrupolar coupling parameters and structure in alpha-quartz phase GeO2

Ab initio band-structure calculations based on density functional theory have been completed for alpha-quartz phase GeO2 to obtain electric-field gradients (efg) for oxygen atoms, including those for GeO2 at elevated pressure and temperature. To interpret the resulting efg values and examine correlations between structure and 17O quadrupolar coupling parameters, additional ab initio self-consistent Hartree-Fock molecular orbital calculations were completed. The quadrupolar coupling constant was found to have a strong dependence on Ge-O distance and angleGe-O-Ge, with the quadrupolar asymmetry parameter being primarily dependent on angleGe-O-Ge. Analytical expressions describing these dependencies consistent with earlier investigations of analogous silicate compounds are also reported.