Regensburg 2013 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MM: Fachverband Metall- und Materialphysik
MM 35: Computational Materials Modelling - Phonons & Phase Stability
MM 35.4: Talk
Wednesday, March 13, 2013, 12:30–12:45, H24
Comparison of phonon frequencies and polarization vectors obtained from fitted force constants or from ab initio force constants — •Christian Illg1, Bernd Meyer2, and Manfred Fähnle1 — 1Max-Planck-Institut für Intelligente Systeme, 70569 Stuttgart, Germany — 2Interdisziplinäres Zentrum für Molekulare Materialien und Computer-Chemie-Centrum, Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
The calculation of electron-phonon scattering matrix elements is necessary in many physical contexts and requires reliable information about phonon frequencies and polarization vectors. One can calculate the phonon frequencies and polarization vectors from the dynamical matrix which is the Fourier-transformed force-constant matrix. The force constants can either be determined by a fit to experimental data or by an ab initio calculation. It is well known that the fitted force constants cannot be determined unambiguously since the polarization vectors are hard to measure and do not enter the fit [1]. A unitary transformation would alter the force constants while leaving the frequencies unchanged (but the polarization vectors would change). We compare the frequencies and polarization vectors in the whole Brillouin zone obtained from fitted force constants and obtained from ab initio force constants [2]. The results are important to make a statement on the reliability of phonon polarization vectors obtained from fitted force constants.
R. S. Leigh, B. Szigeti, V. K. Tewary, Proc. R. Soc. London, Ser. A 320, 505 (1971)
C. Illg, B. Meyer, M. Fähnle, Phys. Rev. B 86, 174309 (2012)