Fig. 3: Schematics of electronic charge displacements in ZrI2.
From: Tunable vertical ferroelectricity and domain walls by interlayer sliding in β-ZrI2
a Wannier functions (top and side views) constructed for the occupied I p (left) and Zr d (middle and right) states. The Wannier functions are presented for one trilayer, and only one p Wannier function at each I site is shown for clarity. Centers of the d orbital Wannier functions are denoted with red circles. b Electronic charge displacements in the centrosymmetric and non-centrosymmetric phases due to interlayer sliding. Vertical shifts of the Wannier centers off their specified atomic positions are schematically shown with arrows. Centers of the d orbital Wannier functions are denoted with green circles. The alternating longer dL and shorter dS zigzag I–I bonds are shown with blue and pink colours, respectively. The inversion center is marked with the black cross.
