Usage: <tt>input = [ <i>tmin tmax cal_shape</i> ]  findcore</tt>

<p>
Determine the average position of defect atoms whose central symmetry deviation (CSD)
parameter <tt>TOPOL</tt> is within the range of <tt>[<i>tmin</i>, <i>tmax</i>)</tt>.
The atoms included in the analysis can be further limited by setting <tt>plot_limits</tt>.
If <tt><i>cal_shape</i> = 1</tt> then the <tt>Principal_Inertia</tt> of the defect cluster
is also computed.

<p>
Assumes that all defect atoms for a single cluster.
