We revisit the quantum mechanical problem of an off-centered impurity in an alkali halide crystal by means of the Pseudo-Jahn-Teller Effect. We confirm that while an impurity may be displaced off-center by virtue of first- order vibronic mixing, reorientational barriers hindering the rotation of an off-centered impurity around a lattice site arise by third-order mixing. The eigenvalue equation of a hindered rotation in-plane is Mathieu's equation. We use the exact eigenstates and eigenvalues to derive a reorientational rate. The rate is compared with available paraelectric data on a Li impurity in KCl.
|Pages (from-to)||377 - 380|
|Number of pages||4|
|Journal||Materials Science Forum|
|Publication status||Published - 1997|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
Petrova, P. C., Ivanovitch, M. D., Georgiev, M., Mladenova, M. S., Baldacchini, G., Montereali, R-M., ... Scacco, A. (1997). Revisiting the off-center impurity problem: Reorientational rate by mathieu functions. Materials Science Forum, 239-241, 377 - 380.