Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 21: Methods: Electronic structure theory I

O 21.3: Vortrag

Dienstag, 24. März 2009, 11:00–11:15, SCH A316

RPA atomization energies of extended systems — •Judith Harl and Georg Kresse — Universiät Wien, Austria

Density functional theory (DFT) applying the local density or generalized gradient approximation (LDA, GGA) leads to bond length errors of the order of 1 % and atomization energies are not reproduced with chemical accuracy. Furthermore, the (semi-)local LDA and GGA do not properly account for long-range van der Waals interactions.

Therefore, the adiabatic connection fluctuation dissipation theorem (ACFDT), which provides in principle an exact expression for the correlation energy, has received increased interest in the recent years (e.g., [1]-[3]). In the present work, we evaluate lattice constants and atomization energies of molecules and extended systems within the ACFDT framework applying the random phase approximation (RPA).

The RPA energy includes the exact exchange energy and a compatible correlation energy that also accounts for long-range van der Waals interactions. We found that the rare-gas solids Ne, Ar, and Kr are well described within the RPA and the correct long-range 1/V² volume dependence is reproduced. For insulators and metals, covalent and ionic bonded systems, RPA lattice constants are found to deviate on average by only 0.25 % from experiment. Atomization energies, however, are throughout too small (≈ 0.2 eV/atom) and the mean error remains close to the results obtained with DFT-PBE.

[1] F. Furche, Phys. Rev. B 64, 195120 (2001). [2] A. Marini, P. García-González, A. Rubio, Phys. Rev. Lett. 96, 136404 (2006) [3] J. Harl, G. Kresse, Phys. Rev. B 77, 045136 (2008)