Table I.

Comparison of average correlation coefficients computed from various correlation functions. Each function was tested across a range of parameters and the best score was saved for each structure and used to calculate the average over a set of 365 structures.

Correlation function	Parameter range	Average correlation coefficient
$\begin{array}{c}{e}^{-{(r/\eta )}^{\kappa }}\hfill \end{array}$	$\begin{array}{cc}1.0\le \eta \le 10.0\hfill & 0.5\le \kappa \le 10.0\end{array}$	0.676
$\begin{array}{c}\frac{1}{1+{(r/\eta )}^{\upsilon }}\hfill \end{array}$	$\begin{array}{cc}1.0\le \eta \le 10.0\hfill & 0.5\le \upsilon \le 10.0\end{array}$	0.673
$\begin{array}{c}\frac{1}{1+{(r/\eta )}^{\upsilon }}{e}^{-{(r/\eta )}^{\kappa }}\hfill \end{array}$	$\begin{array}{c}1.0\le \eta ,\upsilon ,\kappa \le 10.0\hfill \end{array}$	0.670
$\begin{array}{c}\frac{1}{\sqrt{1+{(r/\eta )}^{\upsilon }}}\hfill \end{array}$	$\begin{array}{c}1.0\le \eta ,\upsilon \le 10.0\hfill \end{array}$	0.577