next up previous contents
Next: Discrete memory function of Up: Theory and implementation Previous: VACF within the AR   Contents

Density of states within the AR model
Evaluating $\mathrm{VACF}^{(AR)}(z)$ as given by (4.73) at $z=\exp(i\omega\Delta t)$ yields the density of states within the AR model:
\begin{displaymath}
DOS^{(AR)}(\omega)=\frac{\Delta t}{2}\frac{k_BT}{M} \mathrm{VACF}^{(AR)}
\left(\exp[i\omega\Delta t]\right).
\end{displaymath} (4.78)

Here $M$ is the mass of the tagged atom, $k_B$ is the Boltzmann constant, and $T$ the temperature. Note that the VACF and the density of states within the AR model are entirely determined by the coefficients $a^{(P)}_n$.



pellegrini eric 2009-10-06