Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior, 474 011 MP, India.
J Mol Model. 2012 Jul;18(7):3003-12. doi: 10.1007/s00894-011-1296-9. Epub 2011 Nov 26.
The pressure-induced crystal properties of Eu chalcogenides were investigated using two different models: a modified charge-transfer potential model consisting of Coulomb screening due to the delocalization of the f electron of the rare earth atom, and modified by covalency and zero-point energy effects along with attractive and repulsive interactions; and a charge-transfer model that excluded the covalency and zero-point energy effects in the previous model. Both models were used to visualize the effect of covalency on the mechanism of interaction of the constituent atoms. Eu chalcogenides transform from the Fm3m to the Pm3m phase under the influence of sufficient pressure (P(T) = 39.52, 21.01, 14.31, and 10.58 GPa), and their equations of state indicated decreases in volume during this phase transition of 6.38, 12.32, 12.76, and 11.15%, respectively, for EuO, EuS, EuSe, and EuTe. The results obtained from the models were in good agreement with corresponding experimental data. The elastic constants and Debye temperatures were also computed at normal and high pressures. Both of the models were found to be capable of successfully explaining these properties.
采用两种不同模型研究了 Eu 硫属化物的压力诱导晶体性质：一种是基于稀土原子的 f 电子离域的库仑屏蔽的修正电荷转移势模型，并通过共价键和零点能效应以及吸引力和排斥力进行修正；另一种是排除前一种模型中共价键和零点能效应的电荷转移模型。这两种模型都用于可视化共价键对组成原子相互作用机制的影响。Eu 硫属化物在足够压力的影响下（P(T) = 39.52、21.01、14.31 和 10.58 GPa）从 Fm3m 相向 Pm3m 相转变，其状态方程表明在这个相变过程中体积分别减少了 6.38%、12.32%、12.76%和 11.15%，分别对应于 EuO、EuS、EuSe 和 EuTe。模型得到的结果与相应的实验数据吻合较好。在正常和高压下还计算了弹性常数和德拜温度。两种模型都被证明能够成功解释这些性质。
