Figure 3: Analysis of structural distortions in α-RuCl3 films.
From: Atomic-scale observation of structural and electronic orders in the layered compound α-RuCl3
(a) DFT-calculated relaxed structure of α-RuCl3 unit cell. The equilibrium length of Ru–Cl bonds found in DFT is 236 pm. The Cl–Ru–Cl bond angle at the shared octahedral edges in the relaxed structure is ≈86.3°, whereas the rest of Cl–Ru–Cl angles are approximately 91.3°. (b) Cl–Cl inter-column distances in unperturbed lattice (D0)17,23, DFT calculations (DDFT), and experimental STEM data (DSTEM). (c) DFT-based coordinates of ABC-stacked α-RuCl3 cell superimposed on experimental STEM image. The white arrows schematically show the displacements of Cl columns. (d) Principal component analysis of normal modes of displacement for M=90 unit cells (810 atomic columns); the center of the mass of the entire effective unit cell is chosen as origin. The principal component analysis-derived first three eigenmodes are presented as vectors of deformation from columns position in the averaged cell. Colouring scheme: first three displacement modes are described by blue, red and green arrows, respectively. The length of the arrows is magnified by a factor of 20. The dashed rhombus in c,d schematically denotes the effective unit cell.
