\begin{table} %t2
       \caption{Parameters used for the dielectric function $\delta \epsilon^{f}$.}
    \label{drudeparameter}
    \begin{tabular}{ll|c}
       \hline
       \hline
        \multicolumn{2}{c|}{Parameter} & Value \\
        \hline
        Plasma frequency (298 K)$^a$& $\omega_{\rm p}$ [s$^{-1}$] & $5.090\times 10^{15}$ \\
        Internal collision rate (298 K)$^a$&
        $\Gamma_{\rm i}$ [s$^{-1}$] & $2.693\times 10^{13}$ \\
        Fermi velocity$^b$ & 
$v_{\rm F}$  [cm/s] & $1.98\times 10^8$ \\ \hline
    \end{tabular}
    \smallskip \\
   $^a$ Fit parameters with single Drude term. \\
   $^b$ Taken from Ashcroft \& Mermin (\cite{Ashcroft76}).
      \end{table}