A theoretical investigation of the relative stabilities of Fe-free clinozoisite and orthozoisite

摘要

The relative stabilities of orthozoisite, Ca_2Al_3[O|OH|Si_2O_7|SiO_4], space group Pnma, and the monoclinic polymorph, clinozoisite, space group P2_1/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 B_(ortho) = 117.5(1.7) GPa and B_(clino) = 136(4) GPa.