The generalized X alpha method, based on a local, energy-independent operator derived from the exchange-correlation potential of the local-density approximation by changing the weight of the exchange term, is revisited with the aim of building an optimized starting point for band-structure calculations within the GW method. We find that the optimal choice coincides with the unmodified local-density approximation potential, i.e., with alpha = 2/3. Moreover, we show that the use of an X alpha method to mimic the self-energy effects in the calculation of absorption spectra leads to worse results than the simpler "scissors operator" approach.

Phenomenological approximations to the self-energy operator by a generalized X alpha method / V. Olevano, G. Onida, R. Del Sole. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 61:3(2000), pp. 1912-1917.

Phenomenological approximations to the self-energy operator by a generalized X alpha method

G. Onida
Secondo
;
2000

Abstract

The generalized X alpha method, based on a local, energy-independent operator derived from the exchange-correlation potential of the local-density approximation by changing the weight of the exchange term, is revisited with the aim of building an optimized starting point for band-structure calculations within the GW method. We find that the optimal choice coincides with the unmodified local-density approximation potential, i.e., with alpha = 2/3. Moreover, we show that the use of an X alpha method to mimic the self-energy effects in the calculation of absorption spectra leads to worse results than the simpler "scissors operator" approach.
Settore FIS/03 - Fisica della Materia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/192168
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