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First‐principles theory for the equations of state of minerals at high pressures and temperatures: Application to MgO
Author(s) -
Hemley R. J.,
Jackson M. D.,
Gordon R. G.
Publication year - 1985
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl012i005p00247
Subject(s) - thermal expansion , equation of state , thermodynamics , thermal , materials science , volume (thermodynamics) , atmospheric temperature range , phonon , ab initio quantum chemistry methods , high pressure , drop (telecommunication) , ambient pressure , ab initio , condensed matter physics , physics , molecule , quantum mechanics , telecommunications , computer science
The results of a first‐principles model for the equation of state of MgO from ambient to combined pressure‐temperature conditions assumed for the earth's lower mantle are presented. Ab initio electron‐gas pair potentials are used for the short‐range interactions. The thermal contribution to the equation of state is determined from the quasiharmonic phonons calculated from the pair potentials. The model successfully reproduces the room‐temperature compression curve measured to ∼1 Mbar and the thermal expansion at zero pressure. The volume coefficient of thermal expansion (298 K) is calculated to drop to 30% and 18% of the zero‐pressure value at 0.5 Mbar and 1.0 Mbar, respectively.