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Lattice dynamics; MgSiO₃ perovskite; density of states; specific heat; thermal parameters

A lattice dynamical study of the geophysically important mineral MgSiO₃ in its orthorhombic perovskite phase, with space group Pnma (D_2h¹⁶) has been carried out using a rigid ion model, with the potential consisting of Coulombic and short-ranged interactions. With the help of program DISPR, the ionic charges and radii were optimized using the equilibrium conditions. The resulting potential model is employed to predict the elastic constants and the phonon dispersion relations. The computed long wavelength optic modes are in good agreement with the corresponding experimental Raman and infrared active bands. The phonon density of states has been obtained and is used to evaluate the specific heat, the mean square displacements and thermal parameters of atoms.

Narayani Choudhury¹ S L Chaplot¹ K R Rao¹ Subrata Ghose^{1 2}

1. Nuclear Physics Division, Bhabha Atomic Research Centre, Trombay, Bombay - 400 085, India
2. Mineral Physics Group, Department of Geological Sciences, University of Washington, Seattle, Washington - 98195, USA

Published

May 1988

Manuscript received

16 December 1987