Quasiparticle band structures ofβ-HgS, HgSe, and HgTe

Abstract

The electronic structures of mercury chalcogenides in the zincblende structure have been calculated within the LDA, GW (G0W0, "one-shot") and Quasi-particle Self-consistent GW (QSGW) approximations, including spin-orbit (SO) coupling. The slight tendency to overestimation of band gaps by QSGW is avoided by using a hybrid scheme (20 % LDA and 80 % QSGW). The details of the GW bands near the top of the valence bands differ significantly from the predictions obtained by calculations within the LDA. The results obtained by G0W0 depend strongly on the starting wave functions and are thus quite different from those obtained from QSGW. Within QSGW, HgS is found to be a semiconductor, with a Γ6 s-like conduction-band minimum state above the valencetop Γ7 and Γ8 ("negative" SO splitting). HgSe and HgTe have "negative" gaps (inverted band structures), but for HgTe the Γ7 state is below Γ6 due to the large Te SO-splitting, in contrast to HgSe where Γ6 is below Γ7. There appears to be significant differences, in particular for HgSe and HgS, between the ordering of the band edge states as obtained from experiments and theory.

Strain-induced topological insulator phase transition in HgSe

“…Ab initio calculations based on the GW (G is the Green's function and W is the screened Coulomb interaction) scheme find [13][14][15][16] E 0 ≈ −0.32 to −0.58 eV and SO ≈ 0.27 to 0.32 eV, in agreement with experiment.…”

“…Furthermore, it can also give rise to wrong band topologies and effective masses. 28 Thus, we have also carried out calculations employing the modified Becke-Johnson local density approximation (MBJLDA) method, 29 which predicts 28 band gaps, effective masses, and, most importantly, frontier-band ordering that are in very good agreement with the computationally more intense GW 13 and hybrid-functional 30 approaches. Figures 1(a) and 1(b) display the PBE and MBJLDA band structures of the undeformed HgSe, respectively, along two symmetry directions, where the MBJLDA parameter c = 1.2.…”

“…On the other hand, the MBJLDA shifts the 6 state to a higher energy, resulting in E 0 = −0.23 eV and SO = 0.20 eV, in agreement with the values of E 0 = −0.32 eV and SO = 0.27 eV of recent GW calculations. 13 The fact that both the PBE and the LDA 13 exchange correlation functionals for HgSe yield the correct frontier band ordering ( 7 , 8 ) allows for a reliable determination of the topological invariant. PBE exchange correlation functional.…”

Benchmark ofGWmethods for azabenzenes

“…This procedure has been applied successfully to a variety of systems, including strongly correlated materials. [73][74][75][76][77] However, both ev-scGW and QP-scGW may still have a considerable starting-point dependence. 42 They also do not satisfy points (ii) and (iii).…”

LDA+Uand tight-binding electronic structure of InN nanowires

“…However, this method is computationally more complex than LDA+ U, making difficult its application in large systems. 16,17 Among the various empirical approaches, we have chosen to work with the tight-binding method, that has demonstrated its applicability in III-N nanowires. 18 Moreover, this method allows to deal easily with the problem of the dangling bonds at the free surface of the nanowires, 19 and gives an intuitive physical picture of the wave functions in terms of the atomic orbitals.…”