日本金属学会誌

J. Japan Inst. Metals, Vol. 73, No. 8 (2009),
pp. 566-570

First Principles Calculations of Vibrational Free Energy Estimated by the Quasi-Harmonic Approximation

Shigeto R. Nishitani1, Ryohei Takeda1, Hideki Ishii1, Yosuke Yamamoto1 and Tadaaki Kaneko2

1Department of Informatics, Kwansei Gakuin University, Sanda 669-1337
2Department of Physics, Kwansei Gakuin University, Sanda 669-1337,

Abstract:

The quasi-harmonic approximation is a powerful tool for predicting the vibrational free energy using the first principles calculations. This method with the phonon density of states shows reliable estimation of the thermal expansion and the relative stabilities of SiC polytypes. For the binary systems, we derived a cancelling condition of the vibrational free energy change due to the phase separations within the first order approximation in terms of the nearest bond pair interaction.


(Received 2009/5/7)

Keywords:

Einstein lattice, phonon, thermal expansion, SiC, polytypes, binary


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