Ab initio calculation of elastic constants of SiO2 stishovite and alpha-quartz

We present theoretical ab initio results for the elastic constants of two d ifferent phases of SiO2, stishovite and alpha-quartz using the plane-wave-p seudopotential method. Our calculated values are in very good agreement wit h the experimental data as well as some of the existing model calculations. SiO2 is one of the most abundant minerals in the earth's mantle. Therefore , the knowledge of its elastic behavior will be very important from a seism ology point of view. Our calculated sound velocities are presented and are accordingly also in good agreement with those derived from experiment. (C) 1999 American Institute of Physics. [S0021-9606(99)30229-4].