a–c, Local DOS (colour scale) of Dirac semimetal models showing the location and extent of the modes for different orbit hybridization amplitudes: Δ = 0.1 in the two surface layers at the top and bottom surfaces (a); Δ = 0.05 throughout the entire bulk (b); and Δ = 0.2 (c). The system size is Lx = 64, Ly = 100 and Lz ∈ [21, 35], with sharp side walls at both ends; μ = 0.4, W = 0. The upper panels are the trapezoidal x–z cross sections, with the local DOS averaged across y ∈ [0.1Ly, 0.9Ly] to exclude contributions from the modes on the side walls at both ends in the y direction. The lower panels show the x–y cross sections, with the local DOS averaged across the thickness Lz. The chiral modes vanish completely in c.