Figure 1.

Crystal structure and first Brillouin zone of triclinic ReSe₂. (a) View of a single layer seen from above and (b) from the side. Re atoms are coloured blue and Se atoms are yellow. The directions of the lattice vectors a, b and c are indicated; a is defined here as the direction of the rhenium chains, highlighted in red in (a). (c) First Brillouin zone of ReSe₂ indicating the reciprocal lattice vectors a*, b* and c* and the conventional points Γ (0, 0, 0) and Z (0, 0, ±½). The tilted green hexagon indicates a path in reciprocal space around points of the type (±½, 0, 0); the lower gray hexagon shows the pseudo-Brillouin zone defined by the projections of these points onto the real space layer plane, with basis vectors labelled ${\mathit{a}}_{2D}^{⁎}$ and ${\mathit{b}}_{2D}^{⁎}$ and centre Γ’.