Open AccessVibrational and thermodynamic properties of wadsleyite: A density functional study
Author(s) -
Wu Zhongqing,
Wentzcovitch Renata M.
Publication year - 2007
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007jb005036
Subject(s) - helmholtz free energy , infrared , physics , thermodynamics , materials science , quantum mechanics
The vibrational properties of Mg 2 SiO 4 wadsleyite have been calculated over a wide pressure range using density functional perturbation theory (DFPT). Both the normal mode frequencies and their volume dependences are consistent with the available Raman and infrared data. We provide detailed information about vibrational properties that are still not experimentally available. The vibrational density of states (vDOS) is used to calculate the Helmholtz free energy within the quasi‐harmonic approximation (QHA) and other thermodynamic quantities without further approximations. The extensive and successful comparisons with experiments demonstrate once more that the QHA combined with first principles vDOSs can provide accurate thermodynamic properties of minerals over the large pressure‐temperature regime relevant for the Earth.