Effective continuum model of twisted bilayer GeSe and origin of the emerging one-dimensional mode

The electric structure of twisted bilayer GeSe, which shows a rectangular moir\'{e} pattern, is analyzed using $\bm{k}\cdot\bm{p}$ type effective continuum model. model constructed on the basis local approximation method, where lattice system approximated by its untwisted with parallel displacement, and required parameters are fixed help first-principles method. By inspecting twist angle dependence physical properties, we reveal relation between potential under pattern alignment Ge atoms, also resultant one-dimensional flat band, band flattened stronger in specific direction than perpendicular direction. Due to relatively large mass original monolayers, width as small few meV appear angle. This gives us an opportunity explore dimensional crossover platform.