## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

** 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

Wed Mar 19 '14 8:54pm

This message read **522** times