From owner-chemistry@ccl.net Tue Mar 7 23:47:00 2006 From: "Christopher Cramer cramer-.-chem.umn.edu" To: CCL Subject: CCL: PCM and dipole moment Message-Id: <-31143-060307234153-19437-6n0+YjoQTuQNmRhFA/1GxQ-.-server.ccl.net> X-Original-From: Christopher Cramer Content-Type: multipart/alternative; boundary=Apple-Mail-3-274228373 Date: Tue, 7 Mar 2006 21:56:25 -0600 Mime-Version: 1.0 (Apple Message framework v746.2) Sent to CCL by: Christopher Cramer [cramer^^^chem.umn.edu] --Apple-Mail-3-274228373 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Gonzalo, PCM uses the complete density evaluated from the wave function. As such, it is equivalent to a multipole expansion carried to infinite order (although in practice one rarely needs to go beyond about l = 12 for a moderately sized molecule before multipole expansions and PCM agree to within the noise in the respective methods -- lower still when distributed multipoles are used instead of a single-center expansion). For a complete discussion of this and some other points comparing continuum models, see Curutchet, C.; Cramer, C. J.; Truhlar, D. G.; Ruiz Lopez, M.; Orozco, M.; Luque, F. J. "Electrostatic Component of Solvation: Comparison of SCRF Continuum Models" J. Comput. Chem. 2003, 24, 284. Chris On Mar 7, 2006, at 9:13 PM, Gonzalo Jimenez Oses gonzalo.jimenez*dq.unirioja.es wrote: > Sent to CCL by: "Gonzalo Jimenez Oses" [gonzalo.jimenez{:} > dq.unirioja.es] > Dear CCL'ers: > > I wonder if there is any short way to stablish a coherent > relationship between the free solvation energy (or, at least, the > electrostatic part) obtained through a PCM method (IEF-PCM, C-PCM, > D-PCM) and the dipole (or any other multipole) moment of a molecule. > I have read that solvation models based on a multipole moment > expansion (MPE) of the solute charge distribution, like the > Onsagers original model, solvation is described explicitly in terms > of a dipole moment. > However, solvation models based in an apparent surface charge (ASC) > like PCM seem not to take the multipole moments into consideration > in a explicit way. > > Could anyone shed some light into this question, please? > > Thank you very much in advance, > > Gonzalo > > > > -= This is automatically added to each message by the mailing > script =- > To recover the email address of the author of the message, please > change> Conferences: http://server.ccl.net/chemistry/announcements/ > conferences/ > > Search Messages: http://www.ccl.net/htdig (login: ccl, Password: > search)> > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- > +-+-+ > > > -- Christopher J. Cramer University of Minnesota Department of Chemistry 207 Pleasant St. SE Minneapolis, MN 55455-0431 -------------------------- Phone: (612) 624-0859 || FAX: (612) 626-2006 Mobile: (952) 297-2575 cramer|pollux.chem.umn.edu http://pollux.chem.umn.edu/~cramer (website includes information about the textbook "Essentials of Computational Chemistry: Theories and Models, 2nd Edition") --Apple-Mail-3-274228373 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 Gonzalo,

PCM uses the complete = density evaluated from the wave function. As such, it is equivalent to a = multipole expansion carried to infinite order (although in practice one = rarely needs to go beyond about l =3D 12 for a moderately sized molecule = before multipole expansions and PCM agree to within the noise in the = respective methods -- lower still when distributed multipoles are used = instead of a single-center expansion).

For a complete discussion = of this and some other points comparing continuum models, = see

Curutchet, C.; = Cramer, C. J.; Truhlar, D. G.; Ruiz Lopez, M.; Orozco, M.; Luque, F. J. = "Electrostatic Component of Solvation: Comparison of SCRF Continuum = Models" J. Comput. Chem. = 2003, 24, 284.

Chris

On Mar 7, = 2006, at 9:13 PM, Gonzalo Jimenez Oses gonzalo.jimenez*dq.unirioja.es = wrote:

Sent to CCL by: "Gonzalo Jimenez = Oses" [gonzalo.jimenez{:}dq.unirioja.es]
Dear = CCL'ers:

I wonder if there is any short way to stablish a = coherent relationship between the free solvation energy (or, at least, = the electrostatic part) obtained through a PCM method (IEF-PCM, C-PCM, = D-PCM) and the dipole (or any other multipole) moment of a = molecule.
I have read that solvation = models based on a multipole moment expansion (MPE) of the solute charge = distribution, like the Onsagers original model, solvation is described = explicitly in terms of a dipole moment.
However, = solvation models based in an apparent surface charge (ASC) like PCM seem = not to take the multipole moments into consideration in a explicit = way.

Could anyone shed some light into this question, = please?

Thank you very much in advance,




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--


Christopher J. Cramer

University of Minnesota

Department of Chemistry

207 Pleasant St. = SE

Minneapolis, MN 55455-0431

--------------------------

=

Phone:=A0 (612) 624-0859 || FAX:=A0 (612) 626-2006

Mobile: (952) = 297-2575

cramer|pollux.chem.umn.edu<= /FONT>

http://pollux.chem.umn.edu/~cr= amer

(website = includes information about the textbook "Essentials

=A0 =A0 of Computational = Chemistry:=A0 Theories and = Models, 2nd Edition")


=

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