From owner-chemistry@ccl.net Sat Mar 21 16:21:01 2015 From: "=?UTF-8?Q?Andr=C3=A9_Farias_de_Moura?= moura_-_ufscar.br" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51167-150321153740-20855-vSKLrbY1dKzaxDnqS0+bNQ(0)server.ccl.net> X-Original-From: =?UTF-8?Q?Andr=C3=A9_Farias_de_Moura?= Content-Type: multipart/alternative; boundary=001a11349952693e8a0511d19099 Date: Sat, 21 Mar 2015 16:37:32 -0300 MIME-Version: 1.0 Sent to CCL by: =?UTF-8?Q?Andr=C3=A9_Farias_de_Moura?= [moura]_[ufscar.br] --001a11349952693e8a0511d19099 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable not really a Gaussian issue, the frequencies from the standard harmonic oscillator model need to be scaled. Scaling factor depend on your choice of basis set and level of theory, so you need to find out if anybody has ever published a scaling factor for your specific choices (rb3lyp/6-311++g(d,p))= , otherwise you have to obtain the proper factor by yourself. for the unrestricted case, take a look at: J. Phys. Chem. A, 2005, 109 (12), pp 2937=E2=80=932941, for instance. best Andr=C3=A9 On Sat, Mar 21, 2015 at 12:46 PM, Gustavo A Gotelli ggotelli*|* kaliumtech.com wrote: > > Sent to CCL by: "Gustavo A Gotelli" [ggotelli- -kaliumtech.com] > Hi all! > > I'm using G03W for doing an IR frequency calculation using the 6-311g bas= is > set, > # opt freq rb3lyp/6-311++g(d,p) pop=3Dsavemixed geom=3Dconnectivity scf= =3Dtight > > The problem is that results are far from experimental data, with > differences around 300/400 cm-1 between calculated and experimental peaks= . > I guess is because I'm using wrong parameters, perhaps the basis set. > Can somebody suggest how to get results that better fits experimental dat= a? > > Thanks in advance > Gustavo > > > > -=3D This is automatically added to each message by the mailing script = =3D-> > > --=20 _____________ Prof. Dr. Andr=C3=A9 Farias de Moura Department of Chemistry Federal University of S=C3=A3o Carlos S=C3=A3o Carlos - Brazil phone: +55-16-3351-8090 --001a11349952693e8a0511d19099 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
not really a Gaussian issue, the frequencies from the stan= dard harmonic oscillator model need to be scaled. Scaling factor depend on = your choice of basis set and level of theory, so you need to find out if an= ybody has ever published a scaling factor for your specific choices (rb3lyp/6-311++g(d,p)), otherwise you have to obtai= n the proper factor by yourself. for the unrestricted case, take a look at:= =C2=A0J. Phys. Chem. A,=C2=A02005,=C2=A0109=C2=A0(12), pp 2937=E2=80=932941, for instance.

<= span style=3D"color:rgb(0,0,0);font-family:Helvetica,Arial,sans-serif;font-= size:12px;line-height:16.6399993896484px">best

Andr=C3=A9

On Sat, Mar 21, 2015 at 12:46 PM, Gustavo= A Gotelli ggotelli*|*kaliumtech.com = <owner-chemistry-.-ccl.net> wrote:

Sent to CCL by: "Gustavo A Gotelli" [ggotelli- -kaliumtech.com]
Hi all!

I'm using G03W for doing an IR frequency calculation using the 6-311g b= asis
set,
# opt freq rb3lyp/6-311++g(d,p) pop=3Dsavemixed geom=3Dconnectivity scf=3Dt= ight

The problem is that results are far from experimental data, with
differences around 300/400 cm-1 between calculated and experimental peaks.<= br> I guess is because I'm using wrong parameters, perhaps the basis set. Can somebody suggest how to get results that better fits experimental data?=

Thanks in advance
Gustavo



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--
_____________

Prof. Dr. Andr=C3=A9 Farias de Moura
Department of Chemistry
Federal University of S=C3=A3o Carlos
S=C3=A3o Carlos - Brazil
phone: +55-16-3351-8090
--001a11349952693e8a0511d19099--