Figure9

Figure 9. Temperature dependence of $$ \Delta {C_2}^* $$ (squares) and best fit using the correlated Einstein model (dashed line), which gives $$ {\nu }_{\parallel } = 13.1 $$ THz and a constant shift $$ |a_{\parallel }| = 0.0036 $$Å$$ ^{2} $$. Circles and solid line are, respectively, the resulting parallel MSRD and the corresponding Einstein model. Error bars have been omitted for clarity.