Subject: Free Energy of Aluminium Hydroxide species.

From: <[email-masked]>
Date: Fri, 03 May 1996 14:13:28 +0930

Hi,

I recently completed a study of the heats of formation of
Al containing hdyroxide species. The program I used was
MOPAC with AM1 and PM3. Is it possible to calculate or estimate
the Gibbs Free Energy of these speices using this or any other
easily available program.

Thanks Andrea

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From: "Frederic Bouyer" <[email-masked]>
Date: Tue, 7 May 1996 10:32:06 -0600

Hello Andrea,

Yes, it is possible to calculate free enthalpy (or all thermochemical
quantities) of species at the temperature you want. But remind that this
thermochemical quantities you could calculate refer to the gas compounds.

I do not know exactly about COSMO routine, if it could be useful for solvated
species (liquid phase), and thermochemistry you might do.

For the gas phase however, with MOPAC, you could use the keyword: THERMO, in
conjunction with the ROT keyword, you must use. The later corresponds to the
symmetry number of the molecule, usefull for the rotational contribution. You
can specify the temperature also.

You can find a complete description of the thermochemistry of gas species at:

http://alcyone.enscp.jussieu.fr/Pages/LECA/GP/FB/MASTER/master_readme.html

an old page I wrote few months ago.

You could use either Gaussian or Gamess. Both codes can extract
thermoquantities you want.
But, in any case, you can extract thermoquantities from every code you have - I
mean from every structure, symmetry number, frequencies you could compute for
the compound under study. If the code you have does not calculate
thermochemical functions (like MOPAC), I might recommend the small scripts I
wrote with Mathematica, or the Macintosh application (easy to use) for
calculating thermochemical functions.
Have a look at:

http://alcyone.enscp.jussieu.fr/Pages/LECA/GP/FB/software.html

and see the MASTER packages (Mathematica scripts) or MacMaster (the Macintosh
application).

I used DMol, which does not calculate at the present ime thermochemical
functions. This is the reason I wrote these programs. Furthermore, you could
estimate with these small programs the error of estimating thermochemical
quantities, if you change a little bit the structure, or the frequencies, just
to see their dependence on the thermochemical functions.

For any question about the use of these scripts or the Macintosh program, you
can be in touch with my friends:

Pascal Hebant  : [email-masked]
Aude Hemery    : [email-masked]
Laurent Joubert: [email-masked]
and myself.

Hope this help. With best regards,

Frederic Bouyer

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__________________________________________________________________________

Frederic Bouyer
Groupe Chimie Corrosion - RNE-EMA
EDF-DER Les Renardieres              Tel:   (33) 1-60-73-69-65
Route de Sens, Ecuelles, BP1         Fax:   (33) 1-60-73-68-89    
77250 MORET-SUR-LOING - FRANCE       Email: [email-masked]
__________________________________________________________________________