Fig. 4: Bonding stiffness, charge distribution, and phonon group velocities of AgTl2I3.
From: Strong crystalline thermal insulation induced by extended antibonding states
a The harmonic interatomic force constants (IFCs) for the nearest neighbor atom pairs in AgTl2I3. The inset shows the total charge density of AgTl2I3, where an isosurface of the charge density has been visualized at 0.051 e/Bohr3. b Calculation of the frequency-dependent phonon group velocities of AgTl2I3 and comparison with the maximum of the acoustic phonon group velocities of typical thermal insulation materials at 300 K. The experimentally measured longitudinal (vL) and transverse (vT) sound velocities of AgTl2I3 are also marked for comparison.
