Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 13: Poster 1

HL 13.10: Poster

Montag, 26. März 2007, 15:00–17:30, Poster A

Adiabatic-Connection Fluctuation-Dissipation Theorem for rare-gas crystals — •Judith Harl and Georg Kresse — Sensengasse 8/12 , 1090 Wien, Österreich

Kohn-Sham density functional theory (DFT) has shown to be an efficient and adequate method to describe a wide range of materials properties. Nevertheless, absolute energies are not within chemical accuracy and the Van-der-Waals interaction is not reproduced correctly due to the inaccurate representation of the long range part of the correlation energy. Improvements can be achieved by the adiabatic-connection fluctuation-dissipation theorem (ACFDT), which links the dielectric response of the non-interacting Kohn-Sham system to the correlation energy. Since calculations of the dynamical response function became tractable, first ACFDT calculations, mostly in the random-phase approximation (RPA), have been undertaken [1,2]. In the present work we focus on the rare gas crystals (Ne,Ar,Kr), representative for weakly bonded Van-der-Waals systems. In the local density approximation (LDA) the DFT lattice constants and cohesive energies show large deviations from experiment and the generalised gradient approximation (GGA) fails completely. Applying the ACFDT-RPA, we found that the error in the lattice constant is decreased from 10% for Ne and 6% for Ar (LDA) to under 1%. For Kr the lattice constant is within 3.5% of experiment. The error in the cohesive energy becomes 4 times smaller than in the LDA.

[1] F. Furche, Phys. Rev. B 64 (2001) 195120.

[3] A. Marini et al., Phys. Rev. Lett. 96 (2006) 136404.