论文标题
Cubic Fullerides中的Jahn-Teller效应A $ _ {3} $ C $ _ {60} $
Jahn-Teller effect in cubic fullerides A$_{3}$C$_{60}$
论文作者
论文摘要
与孤立的c $ _ {60}^{3 - } $离子相比，其特征是在最低绝热势能表面（APE）的底部的三二维等电位槽（Jahn-Teller（JT）在Cuticic Fullerides中的效应都受到c $ lipe co $ lipe的相互作用的额外影响。这导致了JT稳定能的改变，并导致每个富勒烯位点的槽的翘曲，以及在不同部位的JT畸变的相互作用。在这里，我们在三个FCC Fullerides中使用A = K，RB，CS和CS $ _3 $ c $ _ {60} $的三个FCC富勒里德（A15）结构研究了这些效果。在c $ _ {60} $站点和声子光谱处的轨道振动耦合常数的DFT计算已用于完全有序的晶格（1 c $ _ {60} $/U.C。）。基于它们，已经评估了局部JT畸变的弹性响应函数，并研究了最低的猿类。为此，已经得出了所有位点的槽坐标功能的后者的表达式。结果表明，与孤立的c $ _ {60}^{3 - } $相比，JT稳定能量略有增加，并且发生了很少的MEV的槽。 JT畸变在最近和下一个最邻里的富勒烯位点上的相互作用的数量级相似。这些效果首先是由于c $ _ {60} $位点与邻居碱原子的位移的相互作用而产生的，并且在FCC富勒底层中比在A15化合物中更为明显。这项研究的结果支持了c $ _ {60} $ cubic a $ _3 $ c $ _ {60} $的c $ _ {60} $站点的JT变形的独立旋转的图片。
Compared to isolated C$_{60}^{3-}$ ions, characterized by a threedimensional equipotential trough at the bottom of the lowest adiabatic potential energy surface (APES), the Jahn-Teller (JT) effect in cubic fullerides is additionally influenced by the interaction of JT distortions at C$_{60}$ sites with vibrational modes of the lattice. This leads to modification of JT stabilization energy and to the warping of the trough at each fullerene site, as well as to the interaction of JT distortions at different sites. Here we investigate these effects in three fcc fullerides with A=K,Rb,Cs and in Cs$_3$C$_{60}$ with bcc (A15) structure. DFT calculations of orbital vibronic coupling constants at C$_{60}$ sites and of phonon spectra have been done for fully ordered lattices (1 C$_{60}$/u.c.). Based on them the elastic response function for local JT distortions has been evaluated and the lowest APES investigated. To this end an expression for the latter in function of trough coordinates of all sites has been derived. The results show that the JT stabilization energy slightly increases compared to an isolated C$_{60}^{3-}$ and a warping of the trough of few meV occurs. The interaction of JT distortions on nearest- and next-nearest-neighbor fullerene sites is of similar order of magnitude. These effects arise first of all due to the interaction of C$_{60}$ sites with the displacements of neighbor alkali atoms and are more pronounced in fcc fullerides than in the A15 compound. The results of this study support the picture of weakly hindered independent rotations of JT deformations at C$_{60}$ sites in cubic A$_3$C$_{60}$.
