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Re: I want to make clear about Solvation Free Energy

Alex Granovsky
gran@classic.chem.msu.su


Dear Atthar,

I'm sorry for such a huge delay with my reply.

In brief, the correct expression for the solvation free energy
is still actively discussed in the literature. There are at least
two different points of view on this problem. The first one is
advocated by Klamt and coworkers and the second one is advocated by
Cramer and Truhlar and coworkers.

Some useful references are:

Ho J., Klamt A., Coote M.L. Comment on the correct use of continuum solvent models. J. Phys. Chem. A (2010), 114(51), 1344213444

(in the case you do not have access, this paper can be found here: http://pcss.xmu.edu.cn/old/users/xlu/group/download/correct_use_of_sm.pdf )

and

Raphael F. Ribeiro , Aleksandr V. Marenich , Christopher J. Cramer, and Donald G. Truhlar. Use of Solution-Phase Vibrational Frequencies in Continuum Models for the Free Energy of Solvation. J. Phys. Chem. B, 2011, 115 (49), pp 1455614562

(this paper is available via Research Gate)

Kind regards,
Alex Granovsky





On Sat May 2 '15 4:33pm, atthar wrote
-------------------------------------
>I have read about the thread about solvation free energy in these threads.

>1. http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C397f033dblT9-8810-394-00.htm
>2. http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C35ce138fb6Xt-8836-805+00.htm

>However, I want to make clear about it.

>In first thread, it is said that (for HF system in gas phase, benzene phase and water phase), in gas phase we do not include thermal correction (G total) from vibrational analysis, so we compare directly the electronic energy from gas phase to "free energy" obtained from PCM calculation, in this case in benzena and water. So, solvation free energy = "free energy" in solvent - "free energy" in gas phase without thermal correction from vibrational analysis

>in second thread, i conclude that the
>Gsoln = Esoln + Gnes + ΔGcorr_gas

>Which one is correct?

>How if i have another opinion when we want to calculate solvation free energy? My opinion is like this :

>solvation free energy = free energy in solvent - free energy in gas phase

>Free energy in solvent = Electronic energy in solvent + G total in solvent
>where G total in solvent is thermal correction obtained from vibrational analysis in solvent using PCM method

>And,

>Free energy in gas phase = Electronic energy in gas phase + G total in gas phase
>where G total in gas phase is thermal correction obtained from vibrational analysis in gas phase

>Can my opinion be accepted?

>Thank you very much for your answer and your attention.

>Best regards,
>atthar


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