On the calculation of the macroscopic polarisation induced by an optic phonon
- 20 September 1980
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 13 (26) , 4893-4903
- https://doi.org/10.1088/0022-3719/13/26/011
Abstract
The author derives a simple expression for the average polarisation P induced by an optic phonon within the Born-Oppenheimer approximation. The calculation for P requires a knowledge of the electronic wavefunctions and energies in both the undistorted crystal and the distorted crystal with a 'frozen-in' optic phonon. The expression is correctly boundary-insensitive and is the proper starting point for the calculation of both linear and non-linear contributions to the polarisation, i.e. effective charges. Specifying a pseudopotential formalism and taking the small displacement limit the author recovers the formula of Vogl (1978) for ZT*. Finally a simple model of a diatomic chain of atoms is discussed to show explicity that anharmonic effects are important if ZT* is large.Keywords
This publication has 7 references indexed in Scilit:
- The infrared effective charge in IV-VI compounds. II. A three dimensional calculationJournal of Physics C: Solid State Physics, 1979
- The infrared effective charge in IV-VI compounds. I. A simple one-dimensional modelJournal of Physics C: Solid State Physics, 1979
- Dynamical effective charges in semiconductors: A pseudopotential approachJournal of Physics C: Solid State Physics, 1978
- Structural instabilities and transverse effective charges in IV–VI compoundsSolid State Communications, 1977
- Comment on calculations of electric polarization in crystalsPhysical Review B, 1974
- Spin density wave and soft phonon mode from nesting Fermi surfacesJournal of Physics F: Metal Physics, 1973
- Pseudopotential Calculation of Transverse Effective Charges for III-V and II-VI Compounds of the Zinc-Blende StructurePhysical Review B, 1972