Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 13: Theory of electronic structure

HL 13.2: Vortrag

Montag, 25. Februar 2008, 16:30–16:45, EW 202

Hybrid density functionals for calculating the lattice dynamics of semiconductors — •Kerstin Hummer and Georg Kresse — Vienna University, Sensengasse 8/12, 1090 Vienna, Austria

We present the ab initio study of the lattice dynamics of group-IV tetrahedral semiconductors, i.e., cubic diamond, silicon, germanium, and grey tin as well as α-quartz by a frozen phonon approach. The main objective of this work is to examine the performance of the screened hybrid density functional proposed by Heyd, Scuseria and Ernzerhof (HSE03) [1] for calculating phonon dispersion curves. The HSE03 has been very successful in describing the structural, electronic, and thermochemical properties of many solids comprising insulators, semiconductors as well as metals [2]. Within density functional theory (DFT), the widely utilized exchange-correlation functionals LDA and GGA show deficiencies in accurately describing the shallow d electrons, which is particularly important in the case of germanium and grey tin. While for both, DFT-LDA yields a wrong (metallic) ground state and considerably underestimated phonon frequencies, the HSE03 functional significantly improves the results regarding the ground state solution, the theoretical lattice constant and thus the lattice dynamics. The presented ab initio phonon dispersions are compared to experimental data and reviewed in the context of previously reported theoretical findings, where particular emphasis is also placed on analyzing its sensitivity to the lattice constant utilized in the calculations.

[1] J. Heyd et al., J. Chem. Phys. 118, 8207 (2003)

[2] J. Paier et al., J. Chem. Phys. 124, 154709 (2006)