Molecular dynamics simulation of MgSiO3 perovskite and the 660-km seismic discontinuity

摘要: Molecular dynamics (MD) simulation is applied to MgSiO3 perovskite (Pv), in which breathing shell model (BSM) developed for oxygen ions take account of non-central forces crystals. MD with BSM found be very successful accurately reproducing the observed structural and elastic properties Pv over wide temperature pressure ranges where experimental data are available. Based on newly together previously obtained each MgO periclase (Pc) Mg2SiO4 spinel (Sp), we use predict density contrast between (Mg,Fe)2SiO4 Sp (Mg,Fe)SiO3 plus (Mg,Fe)O magnesiowustite (Mw) at high-temperature high-pressure conditions corresponding 660-km seismic discontinuity, compare resulting seismologically measured data. Comparison (8.4%) a value (5%) recently by analysing reflected P S waves from discontinuity requires an content this 60% volume, harmony about 60 vol.% pyrolite composition; while PREM (9.3%) demands unreal more than 100% discontinuity.