A local-density approximation for the exchange energy functional for excited states: The band-gap problem

Abstract

We present excited states density functional theory (DFT) to calculate band gap for semiconductors and insulators. For the excited states exchange-correlation functional, we use a simple local density approximation (LDA) like functional and it gives the result which is very closed to experimental results. The linear muffin-tin potential is used to solve the self consistent Kohn-Sham equation.

Excited-state pair-density-functional theory

“…In another paper, Samal and Harbola [30] proposed a different criterion. Harbola and co-workers also developed a local spin density functional approximation by splitting k space and obtained accurate excitation energies [31][32][33][34][35][36][37].…”

Augmented Space Recursion Code and Application in Simple Binary Metallic Alloy

“…The routines in this module are again those in the Stuttgart LMTO47, but modified to read the inputs for both the two constituents of the alloy. -At this point there is a choice of using either the standard DFT exchangecorrelation potentials or, alternatively, there is a branch module Harbola-Sahni which sets up the Harbola-Sahni potential for the study of excited states [19].…”

“…This module is called by the routine lmasr. This main module is divided into five smaller modules : -At this point there is a choice of using either the standard DFT exchangecorrelation potentials or, alternatively, there is a branch module Harbola-Sahni which sets up the Harbola-Sahni potential for the study of excited states [19]. We then proceed to calculate the total density of states and the Fermi energy.…”

Is it possible to construct excited-state energy functionals by splitting k-space?

“…For detailed derivation of these equations, we refer the reader to the next section. Employing the exchange energy functional developed by us, we have been performing accurate calculations [21,22,23,24] of excited-state energies of a variety of systems including the band gaps [32] of a wide variety of semiconductors in the recent past.…”