Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Electronic Structure Theory: General I
O 28.10: Vortrag
Dienstag, 13. März 2018, 12:45–13:00, MA 141
Energy gaps of low-dimensional many-electron systems from Kohn-Sham quantities: Exchange-only approximations — •Alberto Guandalini1, Carlo Andrea Rozzi2, Esa Räsänen3, and Stefano Pittalis2 — 1Dept. FIM, University of Modena and Reggio Emilia, Italy — 2Center S3, CNR - Istituto Nanoscienze, Modena, Italy — 3Dept. of Physics, Tampere University of Technology, Tampere, Finland
The electron addition energies of two-dimensional (2D) quantum dots are commonly obtained from the ground-state (gs) energies of systems with N−1, N, and N+1 electrons [1]. In this work we assess two alternative methods to calculate the addition energies. They resort to (a) the difference of the eigenvalues of the highest- ccupied Kohn-Sham (KS) orbitals for systems with N and N+1 electrons [2]; and (b) the KS gap plus the discontinuity of the exchange-correlation potential – through KS quantities for systems with N electrons [3]. While the original definition of the addition energy involves self-consistent gs calculations for three different systems, method (a) involves two of such calculations, and method (b) only one. At the exchange-only level, we analyze the performance of standard semi-local and (direct) potential approximations. We find that method (b) allows us to reduce the computational effort, yet maintaining the accuracy.
[1] Reimann and Manninen Rev. Mod. Phys. 74, 1283 (2002) [2] Capelle et al. Phys. Rev. Lett. 99, 010402 (2007) [3] Chai and Chen, Phys. Rev. Lett. 110, 033002 (2013)