For the perovskite structure type, sketch example LA (longitudinal acoustic), TA (transverse acoustic), LO (longitudinal optical)…

For the perovskite structure type, sketch example LA (longitudinal acoustic), TA (transverse acoustic), LO (longitudinal optical) and TO (transverse optical) atomic vibrational modes at both k (0,0,0) and k=(0,0,τ/a). (g) 18 m