Debye-Waller factor in Cu: A Green's function approach
Debye-Waller factor in Cu: A Green's function approach
复制标题
Cu 中的德拜-沃勒因子：格林函数方法
DOI：
10.1080/01418639608240323
复制
发表时间：
1996
期刊：
影响因子：
--
通讯作者：
E. Sternin
中科院分区：
文献类型：
--
作者：
R. Shukla;E. Sternin
本文利用Cowley和Shukla在早期非谐性计算中成功使用的模型计算了Cu的Debye-Waller因子。目前的计算是使用准调和理论、最低阶（λ2）非调和微扰理论和绿色函数（GF）方法进行的，该方法对λ2−型非调和项的无穷级数求和。Shukla和Hubschle在早期的工作中引入的GF的自能的立方贡献的静态近似ω → 0被进一步证明是合理的，因为在高温极限下，λ2非谐贡献（立方和四次）对亥姆霍兹自由能的精确结果在这个近似中给出。用λ2微扰理论（PT）和GF方法对改进的莫尔斯势也得到了计算结果。GF结果与实验穆斯堡尔谱和X射线数据在整个温度范围内，300 K ~ 120 K。
Abstract We have calculated the Debye-Waller factor (DWF) of Cu from a model that was used successfully in earlier calculations of anharmonicity by Cowley and Shukla. The present calculation has been carried out using quasiharmonic theory, the lowest-order (λ2) anharmonic perturbation theory, and a Green's function (GF) method which sums an infinite series of the λ2−type anharmonic terms. The static approximation ω → 0 in the cubic contribution to the self-energy of the GF, introduced in the earlier work on the DWF by Shukla and Hubschle is further justified by showing that in the high-temperature limit the exact results for the λ2 anharmonic contributions (cubic and quartic) to the Helmholtz free energy are given in this approximation. Results for the DWF are also obtained for a modified version of the Morse potential with λ2 perturbation theory (PT) and the GF method. The GF results are in excellent agreement with the experimental Mossbauer and X-ray data in the entire temperature range, 300 K T 120...