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Time Correlation Analysis

The dynamics time correlation statement computes different time autocorrelation functions averaged over a set of atoms for NCORS time steps. It is possible to select the included atoms by definition of a shell around a reference point. To specify the time step for the correlation function averaging, one should use the SKIP parameter in the trajectory statement. If the number of selected atoms is exactly one, the long time limit of the correlation function is shifted to zero.

The following correlation functions can be evaluated: positional auto correlation function

$\begin{displaymath}\mbox{AC}(\tau)=<R(t)*R(t+\tau)>\end{displaymath}$

mean square displacement correlation function

$\begin{displaymath}\mbox{MSD}(\tau)=<(R(t)-R(t+\tau))^2>\end{displaymath}$

and velocity autocorrelation function

$\begin{displaymath}\mbox{VAC}(\tau)=<V(t)*V(t+\tau)>\end{displaymath}$

where $V(t)={{dX(t)}\over{dt}}$ .

Subsections

Syntax

Xplor-NIH 2025-03-21