(color online) (a) A top view of the crystal structure of K₂Cr₃As₃ with the c axis along the linear Cr₃As₃ chain. (b) Anisotropic resistivity of K₂Cr₃As₃ single crystals, from which a 3D-to-1D dimension crossover can be seen in the case of (i.e., electric current flowing perpendicular to the chain direction). (c) Calculated band structure of nonmagnetic K₂Cr₃As₃. The inset shows comparison between relativistic (in dark violet) and non-relativistic (in grey) results (from Ref. [30]). (d) Fermi-surface sheets (non-relativistic result).