Fig. 5.

Frequency dependence of broadening for the T₂ excitations at the investigated values of λ . (A) Ω dependence of the broadening ${\mathrm{\Gamma }}_{T_2}$ at the indicated values of λ. Red and green solid lines are the best power-law fits of the form ≃Ω^α to the data in the high $\left(\mathrm{\Omega }>{\mathrm{\Omega }}_{T_2}^{\text{IR}}\right)$ and intermediate $\left(\mathrm{\Omega }<{\mathrm{\Omega }}_{T_2}^{\text{IR}}\right)$ frequency ranges, respectively. ${\mathrm{\Omega }}_{T_2}^{\text{IR}}$ is indicated by the vertical dashed lines in all cases except λ = 0.94, where ${\mathrm{\Omega }}_{T_2}^{\text{IR}}$ is comparable to the highest frequency comprised in the vDOS. For λ = 0.94, the low-frequency cross-over to the anharmonic ≃Ω² behavior is indicated by the blue dashed line. (B) Values of the exponents α extracted from the best fit to the data in A for the high (circles) and intermediate (squares) frequency ranges, respectively. A detailed discussion of these data is included in the text.