From owner-chemistry@ccl.net Wed Jan 24 04:59:01 2007 From: "Marcel Swart marcel.swart*icrea.es" To: CCL Subject: CCL: ONIOM(B3LYP:UFF)=Embed Message-Id: <-33430-070124042717-1459-KIZgy792kc6ArT6qtAI3HQ::server.ccl.net> X-Original-From: Marcel Swart Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed Date: Wed, 24 Jan 2007 10:27:00 +0100 Mime-Version: 1.0 (Apple Message framework v752.3) Sent to CCL by: Marcel Swart [marcel.swart++icrea.es] UFF force field has no electrostatic interactions, therefore the charges should be zero. So this seems correct to me. See for instance: http://towhee.sourceforge.net/forcefields/uff.html On Jan 23, 2007, at 11:56 PM, Tianxiao Yang xiaoyang_guelph(~) yahoo.com wrote: > > Sent to CCL by: "Tianxiao Yang" [xiaoyang_guelph]-[yahoo.com] > Dear Colleagues, > > I am suffering from the problem running ONIOM with electronic- > embedding. The output file shows that the Mulliken atomic charges > of Low Level atoms are zero. > > Here is a very simple input file: > > p ONIOM(TD B3LYP/6-31G(d):UFF)=Embed Geom=Connectivity > > SP test H2O+H2O > > 0 1 0 1 > O > H 1 0.96 > H 1 0.96 2 109.5 > O 3 3.239 1 54.278 2 0.0,0 L > H 4 0.96 3 141.96 1 0.0,0 L > H 4 0.96 3 108.54 1 180.0,0 L > > 1 2 1.0 3 1.0 > 2 > 3 > 4 5 1.0 6 1.0 > 5 > 6 > > Part of the output file showing the Mulliken atomic charges of Low > Level zero. > Mulliken atomic charges: > 1 O -0.786748 > 2 H 0.393374 > 3 H 0.393374 > 4 O 0.000000 > 5 H 0.000000 > 6 H 0.000000 > > Could you please tell me if I missed something in the input file? > Thanks a lot. > > Xiao Yang > Department of Chemistry > University of Guelph > > > > -= 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)> > -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- > +-+-+ > > > –––––––––––––––––––––––––––––––––––––––––––– dr. Marcel Swart ICREA researcher at Institut de Química Computacional Universitat de Girona Campus Montilivi 17071 Girona Catalunya (Spain) fax +34-972-418356 e-mail marcel.swart(~)icrea.es marcel.swart(~)udg.es web http://www.icrea.es/pag.asp?id=Marcel.Swart http://iqc.udg.es/~marcel –––––––––––––––––––––––––––––––––––––––––––– From owner-chemistry@ccl.net Wed Jan 24 07:15:00 2007 From: "Wai-To Chan chan[*]curl.gkcl.yorku.ca" To: CCL Subject: CCL: How do I compute the symmetry number in a TST calculation of a rate constant Message-Id: <-33431-070124071328-3929-Vv8/lDI8lg6si7vU9T00wg|*|server.ccl.net> X-Original-From: Wai-To Chan Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Date: Wed, 24 Jan 2007 07:29:33 -0500 (EST) MIME-Version: 1.0 Sent to CCL by: Wai-To Chan [chan~!~curl.gkcl.yorku.ca] <<<<< I'm a little unclear on how the symmetry number is computed in a TST calculation of the rate constant. Can anyone recommend a clear discussion of this? >>>>>>>> The second edition of Robinson and Holbrook's 'Unimolecular Reactions' explains how the statistical factor for rate constant calculation is evaluated in some details in section 3.9 (pg 56--59). I could be wrong but I can't see how the reaction symmetry number can be computed this way--it has to be done on paper. The easy way out for computation is merely to account for the reaction path degeneracy through inclusion of the rotational symmetry number in the rotation partition functions of the reactants and the transition states in the TST expression. This approach according to the text could result in errors. Wai-To Chan From owner-chemistry@ccl.net Wed Jan 24 14:27:01 2007 From: "Rick Muller rpmuller[#]gmail.com" To: CCL Subject: CCL: How do I compute the symmetry number in a TST calculation of a rate constant Message-Id: <-33432-070124142538-31271-1gqW3Ig8vBDcKX5RS527Mg(-)server.ccl.net> X-Original-From: "Rick Muller" Content-Type: multipart/alternative; boundary="----=_Part_11941_16474387.1169666729493" Date: Wed, 24 Jan 2007 12:25:29 -0700 MIME-Version: 1.0 Sent to CCL by: "Rick Muller" [rpmuller**gmail.com] ------=_Part_11941_16474387.1169666729493 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Thanks very much for all of the great responses. On 1/24/07, Wai-To Chan chan[*]curl.gkcl.yorku.ca wrote: > > > Sent to CCL by: Wai-To Chan [chan~!~curl.gkcl.yorku.ca] > <<<<< > I'm a little unclear on how the symmetry number is computed in a TST > calculation > of the rate constant. Can anyone recommend a clear discussion of this? > >>>>>>>> > > > The second edition of Robinson and Holbrook's 'Unimolecular > Reactions' > explains how the statistical factor for rate constant calculation > is evaluated in some details in section 3.9 (pg 56--59). > I could be wrong but I can't see how the reaction symmetry number can be > computed this way--it has to be done on paper. The easy way out for > computation is merely to account for the reaction > path degeneracy through inclusion of the rotational symmetry number > in the rotation partition functions of the reactants and the transition > states in the TST expression. This approach according to the text could > result in errors. > > Wai-To Chan> > > > -- Rick Muller rpmuller++gmail.com ------=_Part_11941_16474387.1169666729493 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Thanks very much for all of the great responses.

On 1/24/07, Wai-To Chan chan[*]curl.gkcl.yorku.ca <owner-chemistry++ccl.net > wrote:

Sent to CCL by: Wai-To Chan [chan~!~curl.gkcl.yorku.ca]
<<<<<
I'm a little unclear on how the symmetry number is computed in a TST calculation
of the rate constant. Can anyone recommend a clear discussion of this?
>>>>>>>>


        The second edition of Robinson and Holbrook's 'Unimolecular Reactions'
explains how the statistical factor for rate constant calculation
is evaluated in some details in section 3.9 (pg 56--59).
I could be wrong but I can't see how the reaction symmetry number can be
computed this way--it has to be done on paper. The easy way out for
computation is merely to account for the reaction
path degeneracy through inclusion of the rotational symmetry number
in the rotation partition functions of the reactants and the transition
states in the TST expression. This approach according to the text could
result in errors.

Wai-To Chan



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--
Rick Muller
rpmuller++gmail.com ------=_Part_11941_16474387.1169666729493--