Teaching the Jahn鈥揟eller Theorem: A Simple Exercise That Illustrates How the Magnitude of Distortion Depends on the Number of Electrons and Their Occupation of the Degenerate Energy Level
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- 作者：Adam Johannes Johansson
- 刊名：Journal of Chemical Education
- 出版年：2013
- 出版时间：January 8, 2013
- 年：2013
- 卷：90
- 期：1
- 页码：63-69
- 全文大小：316K
- 年卷期：v.90,no.1(January 8, 2013)
- ISSN：1938-1328
文摘
Teaching the Jahn鈥揟eller theorem offers several challenges. For many students, the first encounter comes in coordination chemistry, which can be difficult due to the already complicated nature of transition-metal complexes. Moreover, a deep understanding of the Jahn鈥揟eller theorem requires that one is well acquainted with quantum mechanics and group theory. A comparatively simple way to illustrate the anatomy of the Jahn鈥揟eller effect is presented here. Chemistry teachers are reminded of a sometimes forgotten aspect, namely, that the orbital degeneracy itself is not a sufficient criterion for the Jahn鈥揟eller effect to appear, it is necessary that the occupation of the degenerate energy level is asymmetric. The article can serve as an introduction to the Jahn鈥揟eller theorem, either as a lecture or as a computational exercise.