Europhys. Lett.
Volume 70, Number 1, April 2005
Page(s) 116 - 122
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
Published online 09 March 2005
Europhys. Lett., 70 (1), pp. 116-122 (2005)
DOI: 10.1209/epl/i2004-10462-4

Novel properties of the Kohn-Sham exchange potential for open systems: Application to the two-dimensional electron gas

S. Rigamonti1, C. R. Proetto1 and F. A. Reboredo2

1  Centro Atómico Bariloche and Instituto Balseiro - 8400 S. C. de Bariloche Río Negro, Argentina
2  Lawrence Livermore National Laboratory - Livermore, CA 94551, USA

received 4 October 2004; accepted in final form 3 February 2005
published online 9 March 2005

The properties of the Kohn-Sham (KS) exchange potential for open systems in thermodynamical equilibrium, where the number of particles is non-conserved, are analyzed with the Optimized Effective Potential (OEP) method of Density Functional Theory (DFT) at zero temperature. The quasi-two-dimensional electron gas (2DEG) is used as an illustrative example. The main findings are that the KS exchange potential builds a significant barrier-like structure under slight population of the second subband, and that both the asymptotic value of the KS exchange potential and the inter-subband energy jump discontinuously at the one-subband (1S) $\rightarrow$ two-subband (2S) transition. The results obtained in this system offer new insights into open problems of semiconductors, such as the band-gap underestimation and the band-gap renormalization by photo-excited carriers.

73.20.-r - Electron states at surfaces and interfaces.
73.21.Fg - Quantum wells.

© EDP Sciences 2005