CCL: solvent calc.

 Sent to CCL by: Keith Butler [keeeto2000- -yahoo.co.uk]
   Dear Andreas,
   Just a follow up question to your answer. Would you
 suggest that to find free energy of the solvated
 species using an implict method that the frequency
 calculations should be performed in the gas phase on
 the SOLUTION phase geometries or on gas phase
 structures before applying the thermodynamic cycle.
  Many Thanks,
   Keith Butler
 --- "Andreas Klamt klamt:-:cosmologic.de"
 <owner-chemistry_-_ccl.net> wrote:
 >
 > Sent to CCL by: Andreas Klamt
 > [klamt###cosmologic.de]
 > Dear Aleksandra,
 >
 > sorry to tell you that even in the case of neutral
 > reactions it does not
 > make much sense to apply the standard gasphase
 > methods. All the
 > vibrational free energy contributions are not
 > meaningful in the solvent.
 > The change in vibrational free energy from gasphase
 > to the solvent is
 > already parameterized into the solvent models (see
 > e.g. my CCL
 > contribution from 17.05.2007 ).
 >
 > In my opinion, the only reasonable way to do this in
 > the solvent is to
 > calculate the gasphase reaction and to apply
 > dG_solvation (from a good,
 > quantitative solvation model) to educts and
 > products., i.e. use the
 > thermodynamic cycle
 >
 > Educts, solv ---> Educts, gas --> Products,gas  -->
 > Products, solv
 >
 > Andreas
 >
 >
 > Aleksandra Rudnitskaya aleksandra.rudnit001#umb.edu
 > schrieb:
 > > Sent to CCL by: "Aleksandra  Rudnitskaya"
 > [aleksandra.rudnit001##umb.edu]
 > > Thanks a lot to everyone who sent his answer. I
 > realized I took a wrong example. What if I choose
 > the other system with benzene as a solvent? The
 > questions are the same -
 > > what should I write in input file for
 > optimization, and TS?
 > >
 > >
 > > Thank you
 > >
 > > Aleksandra
 > >
 > >
 > >> Dear CCL members,
 > >>
 > >> Ive just started calculations with solvent. I
 > decided to start from reaction of neutralization
 > NaOH+HCl=H2O+NaCl. As I understand I should
 > calculate
 > >> 1) optimization sodium hydroxide in solvent
 > (water);
 > >> 2) optimization hydrochloric acid in solvent;
 > >> 3) optimization sodium chloride in solvent;
 > >> 4) transition state again in solvent.
 > >> Idea is very similar to that when I calculate
 > rxns in gas phase. Is it correct?
 > >> When I calculate stable species without any
 > solvent I use
 > >> opt freq=noraman RHF/6-31G(d)
 > >> For TS calculations I use
 > >> RHF/6-31G(d) Opt(TS,CalcFC,noeigentest)
 > Freq=noraman
 > >>
 > >> and then charge and multiplicity, and simple
 > Z-matrix in specification part. How should input
 > files look for optimization and searching TS? I know
 > I have to use keyword SCRF, and one of those
 > (SCRF=Dipole, PCM, DPCM, CPCM or IEFPCM), then
 > specify solvent, and probably, dielectric constant
 > somewhere in specification part after matrix. If you
 > may guide me how to create input file itll help a
 > lot.
 > >>
 > >> Thank you very much.>
 > >
 > >
 > >
 > >
 >
 >
 > --
 >
 -----------------------------------------------------------------------------
 > Dr. habil. Andreas Klamt
 > COSMOlogic GmbH&CoKG
 > Burscheider Str. 515
 > 51381 Leverkusen, Germany
 >
 > Tel.: +49-2171-73168-1  Fax:  +49-2171-73168-9
 > e-mail: klamt[A]cosmologic.de
 > web:    www.cosmologic.de
 >
 -----------------------------------------------------------------------------
 > COSMOlogic
 >        Your Competent Partner for
 >        Computational Chemistry and Fluid
 > Thermodynamics
 >
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 >
 >
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