A THEORETICAL INVESTIGATION OF THE RELATIVE STABILITIES OF FE-FREE CLINOZOISITE AND ORTHOZOISITE

Abstract

The relative stabilities of orthozoisite, Ca2Al3[O|OH|Si2O7|SiO4], space group Pnma, and the monoclinic polymorph, clinozoisite, space group P21/m, have been investigated using calculations based on density functional theory. It is found that orthozoisite is more stable than clinozoisite by about 1 kJ mol−1 at zero pressure in the athermal limit. The bulk moduli of the two polymorphs have been calculated to be Bortho=117.5(1.7) GPa and Bclino=136(4) GPa.