Electronic structure calculations with the Tran-Blaha modified Becke-Johnson density functional

Abstract

We report a series of calculations testing the predictions of the Tran-Blaha functional for the electronic structure and magnetic properties of condensed systems. We find a general improvement in the properties of semiconducting and insulating systems, relative to calculations with standard generalized gradient approximations, although this is not always by the same mechanism as other approaches such as the quasiparticle GW method. In ZnO the valence bands are narrowed and the band gap is increased to a value in much better agreement with experiment. The Zn d states do not move to higher binding energy as they do in LDA+U calculations. The functional is effective for systems with hydride anions, where correcting self-interaction errors in the 1s state is important. Similarly, it correctly opens semiconducting gaps in the alkaline earth hexaborides. It correctly stabilizes an antiferromagnetic insulating ground state for the undoped cuprate parent CaCuO2, but seriously degrades the agreement with experiment for ferromagnetic Gd relative to the standard local spin density approximation and generalized gradient approximations. This is due to positioning of the minority spin 4f states at too low an energy. Conversly, the position of the La 4f conduction bands of La2O3 is in reasonable accord with experiment as it is with standard functionals. The functional narrows the Fe d bands of the parent compound LaFeAsO of the iron high temperature superconductors, while maintaining the high Fe spectral weight near the Fermi energy.PACS numbers:

Electronic Structure of Zn3V2O8and Mg3V2O8

“…The electronic structure calculations which was performed by using the TB-mBJ functional had shown that the valence and the conduction bands became narrowed, however the Zn-3d states were not shifted on the energy scale as in the case of GGA+U. Similar behavior was reported for ZnO for the TB-mBJ functional [10] and PBE+U [15]. In Mg 3 V 2 O 8 the main contribution to the valence bands comes from the O-2p electrons that hybridize with the V-3d electrons.…”

“…We used version of meta-GGA functional proposed by Tran and Blaha which is a modified version of the BeckeJohnson exchange potential (TB-mBJ) [9]. The TB-mBJ method gave the values of the band gaps for the various systems which were in a good agreement with both experimental data and more sophisticated methods like for example GW approximation or hybrid functionals [9,10]. The main advantage of the TB-mBJ functional is the scaling like the standard DFT rather than hybrid or GW based functionals [9].…”

Tuning optical properties of transparent conducting barium stannate by dimensional reduction

“…Following the structure optimization, we did electronic structure and optical calculations using the modified Becke-Johnson type potential functional of Tran and Blaha, 42 denoted TB-mBJ in the following. This potential gives band gaps in remarkably good accord with experiment for a wide variety of simple semiconductors and insulators, [42][43][44][45][46] including perovskite stannates. 15 We compared the TB-mBJ results for the undoped compounds with HSE06 calculations as discussed below.…”

Electronic and transport properties of zintl phase AeMg2Pn2, Ae = Ca,Sr,Ba, Pn = As,Sb,Bi in relation to Mg3Sb2

“…15 Unlike standard GGA functionals, which are designed to reproduce total energies and structures but underestimate the band gaps of semiconductors, 16 the TB-mBJ functional cannot be used for total energy calculations, but does yield very much improved band gaps in a wide variety of materials. 15,17 The optical properties were calculated using the optical package of the WIEN2k code, which is based on calculation of the vertical electric dipole matrix elements between occupied and unoccupied states.…”