Subject: rotational entropy in solution

From: "Dr. Paolo Mencarelli" <[email-masked]>
Date: Tue, 9 Jan 1996 10:55:30 -0500

Dear CClers,

Some time ago I posted a question concerning the evaluation of the
rotational entropy in solution.
I received only two answers.
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My original question:

>Hi all,
>I am an organic chemist interested in host-guest chemistry, and I have  the
problem of evaluate the >rotational entropy of a molecule in solution.  
>I am able to evaluate the rotational entropy in the gas phase by using
statistical thermodynamics, i.e. >by the rotational partition function, but
I am not aware of extension of such theory to the liquid >state. 
>
>Does anyone know how to evaluate, even in approximate way, the rotational
entropy of a molecule in >solution?
>Thanks.
>                Paolo Mencarelli

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First answer:

>Hi,
>
>Although I can provide no satisfying answer to your question, I have 
>encountered a paper dealing with free energy calculations of enzyme binding
>including all kinds of entropy effects. The reference: Biochemistry, 1994, 33,
>13977- (au:S. Vajda).
>Recently we have been trying to develop a method to calculate rotational
entropyusing statistical >methods therefore I would appreciate if you could
send me a
>reference list of your method (if it has been published).
>
>Thanks,   Greg Makara

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Second answer:

>Dear Mr Mencarelli,
>
>I do not know if there is a theory for statistical thermodynamic for 
>your problem, but did you ever try semiempirical calculations? I know 
>that the program VAMP is able to calculate, what would happen to the energy 
>if a molecule would be in a solvent. VAMP is distributed by selling, but 
>there are a similiar programs called AMPAC and MOPAC. You can get versions 
>of these via ftp. I have to say, that I never tried such calculations with
AMPAC
>or MOPAC, as we can use VAMP at University on a real Supercomputer. 
>But I would be astonished if this would not work, as VAMP, MOPAC and
>AMPAC are very compatible.
>
>I hope this may help a bit.
>
>Many greetings and I wish you a merry Christmas and a happy new year.
>
>Ralph Puchta
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Any further comments are welcome

Thanks,
        Paolo Mencarelli
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Dr. Paolo Mencarelli
Dipartimento di Chimica Universita' La Sapienza
P.le Aldo Moro, 2  00185 Roma - ITALY
tel 06-49913697 fax 06-490631
E-Mail [email-masked] 
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