Fig. 3. Behavior of Weyl points at closing of the band gap in inversion-asymmetric insulators.

(A) Schematic band structure for the case with dim R_c = 2 and dim R_v = 1. The gap does not close at k₀ in this case. (B) Trajectory of Weyl nodes in the case (i) after pair creation at k₀. (C) Trajectory of Weyl nodes in (ii-2) and in (iii-2). The Weyl nodes move along the C₂ axis. (D) Trajectory of Weyl nodes in the case (iii-1) viewed from different angles. The k₀ point is on the C_2z axis away from a TRIM Γ_i. (E) Trajectory of Weyl nodes in the case (iv-1). In (B) to (E), yellow and green spheres denote monopoles and antimonopoles in k space, respectively, and they are both Weyl nodes.