# How to calculate the free energy from the nwchem output file

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 Mhiranya Member Profile Send PM
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 10:23:07 AM PDT - Sat, Apr 19th 2014 Hi, I would like to know how to calculate the Free energy change from the nwchem output file. Thanks

 Huub Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop Profile Send PM
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 9:51:37 AM PDT - Thu, Apr 24th 2014 Hi Mhiranya, Could you say something more about what you are doing? Are you running dynamics, or do you just want to calculate the free energy at two reaction end points? I need a little more information to be able to give you an answer that is appropriate for your study. Huub

 Mhiranya Member Profile Send PM
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 8:34:54 AM PDT - Fri, Apr 25th 2014 Huub, No, I'm not running dynamics, I'm studying about isomers of Rh catalyst. I want to calculate their free energy change. So, this is the part of the output thermodynamic parameters, however, total enthalpy is missing here. Hope you can help me with this. Thanks ``` Vibrational analysis via the FX method --- with translations and rotations projected out --- --- via the Eckart algorithm --- Projected Nuclear Hessian trans-rot subspace norm:1.2699D-33 (should be close to zero!) ``` From the projected analysis The Zero-Point Energy (Kcal/mol) = 99.33560788 ```center of mass -------------- x = 0.07031235 y = -0.10235627 z = 0.03349458 ``` ```moments of inertia (a.u.) ------------------ 2942.527422606949 16.957400854026 -31.017758287500 16.957400854026 1815.031657939912 44.968030875314 -31.017758287500 44.968030875314 3243.687056532644 ``` ```Rotational Constants -------------------- A= 0.033199 cm-1 ( 0.047764 K) B= 0.020478 cm-1 ( 0.029462 K) C= 0.018534 cm-1 ( 0.026665 K) ``` ```Temperature = 298.15K frequency scaling parameter = 1.0000 ``` ```Zero-Point correction to Energy = 99.258 kcal/mol ( 0.158178 au) Thermal correction to Energy = 108.841 kcal/mol ( 0.173449 au) Thermal correction to Enthalpy = 109.433 kcal/mol ( 0.174393 au) ``` ```Total Entropy = 125.807 cal/mol-K - Translational = 42.477 cal/mol-K (mol. weight = 253.9490) - Rotational = 31.213 cal/mol-K (symmetry # = 1) - Vibrational = 52.117 cal/mol-K ``` ```Cv (constant volume heat capacity) = 52.354 cal/mol-K - Translational = 2.979 cal/mol-K - Rotational = 2.979 cal/mol-K - Vibrational = 46.395 cal/mol-K ```

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