Uniaxial Pressure‐Induced 2D–1D Dimensionality Change in GaSe and Related Materials

2D materials with van der Waals (vdW) gaps between covalently bonded blocks are in the focus of modern semiconductor science and technology. Of special interest is the possibility to control their properties through the vdW gap reconfiguration. Herein, using first‐principles simulations it is demonstrated that uniaxial compression of GaSe, counterintuitively, does not serve to close the gap but, instead, changes the dimensionality from 2D to quasi‐1D, with flat GaSe chains oriented along the applied pressure. The structural change is accompanied by drastic changes in electronic structure. The inability to close the vdW gap to the antibonding nature of Se–Se interactions is attributed.