Topological transition in Pb1-xSnxSe using Meta-GGA exchange-correlation functional

We calculate the mirror Chern number (MCN) and the band gap for the alloy Pb1-xSnxSe as a function of the concentration x by using virtual crystalline approximation. We use the electronic structure from the relativistic density functional theory calculations in the Generalized-Gradient-Approximation (GGA) and meta-GGA approximation. Our results obtained with the modified Becke-Johnson meta-GGA functional, are comparable with the available experimental data for the MCN as well as for the band gap. We advise to use modified Becke-Johnson approximation with the parameter c = 1.10 to describe the transition from trivial to topological phase for this class of compounds.