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Re: What is the way then to calculate free energy in solution (including entropy contribution of a solute etc)?

Alex Granovsky
gran@classic.chem.msu.su


Dear Tatiana,

I'm sorry for the delay with my reply.

>If eq. 4 from Klamt and colleagues is arguable, what is an alternative way to calculate free energy in solution (with entropy contribution of a solute etc…)?
>In the discussion you mentioned in your answer, you proposed to compare electronic energies, but for comparison of a calculation with experimentally observable values (at least with a distribution between different states in the solution) one needs to take into consideration entropy contributions too.

I'd suggest you to use eq. 4 from Klamt and coworkers
with the only difference that ΔGcorr_gas should include
various gas phase vibrational contributions only.
In addition, you should add the following to your input:

 $pcm 
          TABS=the absolute temperature.
          ICAV=1
          IDISP=1
 $end

to compute Gnes of eq. 4.

Alternatively, you can experiment with

 $pcm 
          TABS=the absolute temperature.
          ICAV=1
          IREP=1
          IDP=1  
 $end

See Firefly's manuals for more details on PCM input.

Kind regards,
Alex Granovsky


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