Tinker/perl/s-vib at release · MolSSI-MDI/Tinker

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#!/usr/bin/perl

$file=$ARGV[0]; #tinker vibbig.x output

$from=$ARV[1]; $to=$ARGV[2];

if($#ARGV<2){die "command line syntax: vibbig.x_output first_mode last_mode\n";}

$h=6.6260693*10**-34; #planck

$k=1.3806503*10**-23; #boltzmann

$T=298; #temp

$c=299792458; #light

$g=0;

$lastline=$to+1;

@f=`grep ' Mode ' $file -A $lastline`;

print "@f\n";

for($i=2;$i<=$lastline;$i++){

$v= ((split ' ', $f[$i])[1]); #corrected for cm^-1-->s^-1 units

$v=$v*100*$c;

$g1=$h*$v*(0.5+1/(exp($h*$v/($k*$T))-1));

$g2=$h*$v/(exp($h*$v/($k*$T))-1)-$k*$T*log(1-exp(-$h*$v/($k*$T)));

$g+=($g1-$g2);

}

$g=6.0221415*10**20*($g); #corrected for J-->kJ/mol

print "dGvib $g kJ/mol\n";