Anharmonic correlated Debye model high-order expanded interatomic effective potential and Debye-Waller factors of bcc crystals

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• 作者：Nguyen Van Hung^a ; ^{hungnv@vnu.edu.vn" class="auth_mail" title="E-mail the corresponding author} ; Trinh Thi Hue^a ; Ha Dang Khoa^b ; Dinh Quoc Vuong^c
• 关键词：Debye-Waller factor ; Effective potential ; Correlated Debye model ; Many-body perturbation approach ; Bcc crystals
• 刊名：Physica B: Physics of Condensed Matter
• 出版年：2016
• 出版时间：15 December 2016
• 年：2016
• 卷：503
• 期：Complete
• 页码：174-178
• 全文大小：502 K

文摘

High-order expanded interatomic effective potential and Debye-Waller factors (DWFs) for local vibrational amplitudes in X-ray absorption fine structure (XAFS) of bcc crystals have been studied based on the anharmonic correlated Debye model. DWFs are presented in terms of cumulant expansion up to the fourth order and the many-body effects are taken into account in the present one-dimensional model based on the first shell near neighbor contribution approach used in the derivations of the anharmonic effective potential and XAFS cumulants where Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions for the dispersion relation, correlated Debye frequency and temperature and four first temperature-dependent XAFS cumulants have been derived based on the many-body perturbation approach. Thermodynamic properties and anharmonic effects in XAFS of bcc crystals described by the obtained cumulants have been in detail discussed. The advantage and efficiency of the present theory are illustrated by good agreement of the numerical results for Mo, Fe and W with experiment.