Fig. 4: Mode softening of the lowest frequency A2 vibrational mode in (1) with pressure.
From: High-pressure reversibility in a plastically flexible coordination polymer crystal
a Vibrational frequency of the A2 band as a function of pressure. b Potential energy surface associated with the lowest frequency A2 normal mode in the low-pressure phase of (1). Displacements are shown as regular displacements along the A2 mode eigenvector away from equilibrium. Note that the curves for P =5 GPa and P = 5.5 GPa have been multiplied by 10 for clarity. c Overlay of the A2 normal mode displacement from (grey) η = 0 to (green) η = 4.
