ED Software Files

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* Effective diameter of molecule estimation *
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This AWK script (awk_get_diameter) is used for the estimation of
effective diameter of molecule from MD simulation. It should be
used to estimate the collision frequency from formula:

    v = 4 * d * ( pi / (m * k * T))^(1/2) * P ,

where v - is frequency, d - diameter, m = M/2 - reduced mass of the molecules,
k - Boltzmann constant, T - temperature, P - pressure.

The diameter is estimated from 3 diameters 
  d_{ij} = r_{ij} + rVdW_i + rVdW_j ,
where d - diameter, r - distance between the atoms, rVdW - Van der Waals radius.

They 3 diameters calculated as:
 1) the longest diameter (d0);
 2) the longest diameter projection on the plane, orthogonal to the d0 (d1);
 3) the longest diameter on the direction orthogonal to d0 and d1 (d2).
The script calculates the arithmetical average d_aa = ((d0+d1+d2)/3), 
geometrical d_ga = ((d0*d1*d2)^(1/3)),
and reduced d_red = d0*d1*d2/(d0*d1 + d0*d2 + d1*d2).
These values are averaged over the trajectory starting from some step nmin and 
printed in the end.

The input file should be in XYZ format.

Versions log:

 - 09.11.2015 - first version is released.