Abstract
The nature of the polarization catastrophe previously reported in several defect calculations is analysed. For the commonly used polarizable point dipole model it is shown that a necessary condition for the avoidance of such catastrophes is that the separation of all ion pairs, i, j must be greater than rcrit=(4 alpha i alpha j)1/6 where the alpha i's are the electronic polarizabilities. This requirement is independent of the form of the interionic potential function. This condition is identical with that previously derived by Tosi and Doyama for alkali halide molecules, but it is shown that it applies to all ion pairs in the solid. The effect of these inherent instabilities on the calculated energies of defects and of alkali halide molecules is discussed. It is concluded that the most realistic physical extension of the model which avoids these instabilities is the inclusion of the reduction of polarizability with ionic overlap.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.