期刊
PHYSICAL REVIEW B
卷 80, 期 13, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.80.134304
关键词
-
资金
- University International Visiting Research Grant
- School of Physics, University of Sydney, Sydney, Australia
Using ab initio density-functional perturbation theory the lattice dynamics of Cu2O has been extensively studied. Discrepancies with older neutron-scattering results triggered a neutron-scattering investigation of our own which confirmed the theoretical prediction. Based on the accurate description of the phonon dispersion the vibrational part of the free energy was calculated as a function of lattice constant and temperature. The thermal expansion could be obtained in good agreement with experiments. For T < 300 K negative thermal expansion (NTE) was observed while for higher temperatures normal thermal expansion was obtained. The origin of the NTE is due to anomalous behavior of phonon modes with energies < 20 meV which is highly mode and wave-vector sensitive. Our calculations also showed that free energies based on the exact phonon dispersion and those based on an Einstein-model description (widely used) differed by more than 20%, which clearly indicates the importance of proper phonon-dispersion treatment for obtaining reliable thermodynamic data.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据