LDF pseudopotential calculations of the ?-quartz structure and hydrogarnet defect

Abstract

Abstract. Ab initio LDF theory has been used to study the structure of the hydrogarnet defect in c~-quartz. The predicted structure is in good agreement with the available experimental data. The techniques employed also yield a good model for the structure of a:quartz, giving an average Si-O bond length of 1.62 A and average Si -O -Si angle of 142 ~

The energetics and structure of the hydrogarnet defect in grossular: A computer simulation study

“…The full set of distances, along with H-O-O bond angles, are given in Table 4. These results are similar to those of Purton et al (1992) who, as noted earlier, used ab initio methods to calculate the structure of the hydrogarnet defect in quartz.…”

“…This follows an earlier successful study by Purton et al (1992) of this defect in quartz using LDA electronic structure techniques. However, for the purpose of the present investigation, atomistic simulation methods are sufficient and have the advantage that the calculation of defect formation energies is more straightforward.…”

Ab initio calculations on (OH)4 defects in α-quartz

“…The present paper extends the work of Purton et al (1992) and is entirely consistent with that study. Here we provide thermodynamic and structural data that govern the defect structures of hydrous e-quartz and bear on the mechanism of its hydrolytic weakening.…”

Ab initio potentials for the calculation of the dynamical and elastic properties of ?-quartz

“…In the earlier work of Purton et al (1992) we described the computational method for the geometry optimisation of a 33 atom cluster. We will therefore only discuss the details of the LDF calculation pertinent to the fitting of the potential parameters.…”

“…The cluster was terminated by H atoms at a distance of 1.0 ~. Geometry optimisation of the central nine atoms yielded a structure with Si-O bond lengths of 1.604-1.622~ and an Si-O-Si bond angle of 141.7-142.3 ~ (Purton et al 1992).…”