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| Thermodynamic properties of wadsleyite with anharmonic effect |
| Zhongqing Wu |
| Laboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, Anhui, China |
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Abstract The thermodynamic properties of crystals can be routinely calculated by density functional theory calculations combining with quasi-harmonic approximation. Based on the method developed recently by Wu and Wentzcovitch (Phys Rev B 79:104304, 2009) and Wu (Phys Rev B 81:172301, 2010), we are able to further ab initio include anharmonic effect on thermodynamic properties of crystals by one additional canonical ensemble with numbers of particle, volume and temperature fixed (NVT) molecular dynamic simulations. Our study indicates that phonon–phonon interaction causes the renormalized phonon frequencies of wadsleyite decrease with temperature. This is consistent with the Raman experimental observation. The anharmonic free energy of wadsleyite is negative and its heat capacity at constant pressure can exceed the Dulong–Petit limit at high temperature. The anharmonicity still significantly affects thermodynamic properties of wadsleyite at pressure and temperature conditions correspond to the transition zone.
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Received: 19 November 2014
Published: 13 January 2015
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| Fund:State Key Development Program of Basic Research of China (2014CB845905), the Natural Science Foundation of China (41274087). |
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Corresponding Authors:
Zhongqing Wu
E-mail: wuzq10@ustc.edu.cn
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