From owner-chemistry@ccl.net Sun Jul 27 12:06:01 2008 From: "Sebastian Kozuch kozuchs%a%yahoo.com" To: CCL Subject: CCL:G: Solvation Entropy Message-Id: <-37428-080727080250-19232-uUisTt9BVjBRr6nQmwBD1g+*+server.ccl.net> X-Original-From: Sebastian Kozuch Content-Type: multipart/alternative; boundary="0-1073596331-1217156558=:77771" Date: Sun, 27 Jul 2008 04:02:38 -0700 (PDT) MIME-Version: 1.0 Sent to CCL by: Sebastian Kozuch [kozuchs*yahoo.com] --0-1073596331-1217156558=:77771 Content-Type: text/plain; charset=us-ascii Dear CCLers: Do someone know how to estimate the solvation entropy? Using gaussian you can easily calculate the solvation free energy of a molecule. On the other side, you can calculate the free energy in gas phase. But when doing free energy calculation (using freq keyword) in solvent, the entropy added is mostly the gas phase one, which adds a huge error, since the translational and rotational parts of the entropy are very different in solvent and gas phase. So what should be the best solution? Adding the solvation energy to the energy or to the free energy? Is there something more accurate? Thanks in advance, xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx ..........Sebastian Kozuch........... xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx ...The Lise Meitner-Minerva Center... .for Computational Quantum Chemistry. ...Hebrew University of Jerusalem.... .....kozuchs#yfaat.ch.huji.ac.il..... http://yfaat.ch.huji.ac.il/kozuch.htm xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx --0-1073596331-1217156558=:77771 Content-Type: text/html; charset=us-ascii

Dear CCLers:
Do someone know how to estimate the solvation entropy?
Using gaussian you can easily calculate the solvation free energy of a molecule. On the other side, you can calculate the free energy in gas phase. But when doing free energy calculation (using freq keyword) in solvent, the entropy added is mostly the gas phase one, which adds a huge error, since the translational and rotational parts of the entropy are very different in solvent and gas phase.
So what should be the best solution? Adding the solvation energy to the energy or to the free energy? Is there something more accurate?

Thanks in advance,

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
..........Sebastian Kozuch...........
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
...The Lise Meitner-Minerva Center...
.for Computational Quantum Chemistry.
...Hebrew University of Jerusalem....
.....kozuchs#yfaat.ch.huji.ac.il.....
http://yfaat.ch.huji.ac.il/kozuch.htm
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

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