From owner-chemistry@ccl.net Sat Mar 21 11:05:01 2015 From: "=?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal victor,,fluor.quimica.uniovi.es" To: CCL Subject: CCL:G: problem in Gaussian 03 program Message-Id: <-51164-150321110211-12797-UGDCcJVilowrepIFmAWPkQ_+_server.ccl.net> X-Original-From: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal Content-disposition: inline Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-1 Date: Sat, 21 Mar 2015 15:57:19 +0100 MIME-version: 1.0 Sent to CCL by: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal [victor ~~ fluor.quimica.uniovi.es] On Fri, Mar 20, 2015 at 06:39:17PM -0400, Safiya Ess Amer amersaf85(a)yahoo.com wrote: > I thought about using dummy atom at center of H2 molecule but I > couldn't. I don't know ghost atom, is it same a dummy atom? I frozen > all atoms of the system at suitable coordinates and ran program to get > energy as you said in the 2nd way, but without using dummy atom. The > positions of H2 atoms changed manually each time. I need a way with > automaticaly changing for positions. in other words, scaning of more > than one atom automatically rather than manually. Safiya, 1) g03 is a very old version of the code. If you have finace problems in obtainig a quantum chemistry code try any freeware option: nwchem, gamess, orcad, ... These codes are distributed liberally for a non commercial institution. 2) As you guessed dummy or ghost atoms are basically the same thing. A dummy can be used to build the geometry easily. Depending on the quantum code that you are using you can put a charge on a dummy to build a finite set of charges describing the environment, or you can out a basis function there (floating basis functions), or a pseudopotential (again to model the environment), .... 3) There are too many uses for a ghost/dummy atom to mention them all. Good luck, Dr. Víctor Luaña -- . . "The hardest part in solving a problem is recognizing / `' \ its existence. Learning the causes CAN be the road to /(o)(o)\ the solution." /`. \/ .'\ -- ¿? / '`'` \ "Lo mediocre es peor que lo bueno, pero también es peor | \'`'`/ | que lo malo, porque la mediocridad no es un grado, es una | |'`'`| | actitud" \/`'`'`'\/ -- Jorge Wasenberg, 2015 ===(((==)))==================================+========================= ! Dr.Víctor Luaña ! Mediocre is worse than ! Departamento de Química Física y Analítica ! good, but it is also ! Universidad de Oviedo, 33006-Oviedo, Spain ! worse than bad, because ! e-mail: victor{}fluor.quimica.uniovi.es ! mediocrity is not a grade, ! phone: +34-985-103491 fax: +34-985-103125 ! it is an attitude +--------------------------------------------+ GroupPage : http://azufre.quimica.uniovi.es/ (being reworked) From owner-chemistry@ccl.net Sat Mar 21 12:48:01 2015 From: "Gustavo A Gotelli ggotelli*|*kaliumtech.com" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51165-150321114650-9150-GJ+Keh3e90UsRUzZ3I5yhw###server.ccl.net> X-Original-From: "Gustavo A Gotelli" Date: Sat, 21 Mar 2015 11:46:48 -0400 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 basis set, # opt freq rb3lyp/6-311++g(d,p) pop=savemixed geom=connectivity scf=tight 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 data? Thanks in advance Gustavo From owner-chemistry@ccl.net Sat Mar 21 15:03:01 2015 From: "zborowsk zborowsk[A]chemia.uj.edu.pl" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51166-150321150102-11107-Qx/8eilJSJNHhUaJwHX+eQ]=[server.ccl.net> X-Original-From: zborowsk Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8; format=flowed Date: Sat, 21 Mar 2015 20:00:50 +0100 MIME-Version: 1.0 Sent to CCL by: zborowsk [zborowsk!=!chemia.uj.edu.pl] W dniu 2015-03-21 16:46, Gustavo A Gotelli ggotelli*|*kaliumtech.com napisaÅ‚(a): > 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 > basis > set, > # opt freq rb3lyp/6-311++g(d,p) pop=savemixed geom=connectivity > scf=tight > > 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 > data? > Hi Gustavo Where is such a difference between theory and experiment. Around 100, 1000 or 3000 cm-1. Or you observed it for the whole vibrational spectrum?? > Thanks in advance > Gustavo > > > > -= 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/-- https://www.youtube.com/watch?v=IGyfx3Pmeyk Krzysztof K. Zborowski Faculty of Chemistry Jagiellonian University 3 Ingardena Street 30-060 Krakow Poland phone: +48(12)663-2067 email: zborowsk*o*chemia.uj.edu.pl gg 3817259 skype kzys70 www.chemia.uj.edu.pl/~zborowsk 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



-=3D This is automatically added to each message by the mailing script =3D-=
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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-- From owner-chemistry@ccl.net Sat Mar 21 17:04:00 2015 From: "Wojciech Kolodziejczyk dziecial^-^icnanotox.org" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51168-150321170251-7132-zVhBJnY3NBVFmwxvvX39IA*server.ccl.net> X-Original-From: Wojciech Kolodziejczyk Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Sat, 21 Mar 2015 16:02:42 -0500 MIME-Version: 1.0 Sent to CCL by: Wojciech Kolodziejczyk [dziecial(~)icnanotox.org] It's not a gaussian thing. Did you scale it? Here is a website with scaling factors. Find yours http://t1.chem.umn.edu/freqscale/index.html 2015-03-21 14:00 GMT-05:00 zborowsk zborowsk[A]chemia.uj.edu.pl : > > Sent to CCL by: zborowsk [zborowsk!=!chemia.uj.edu.pl] > W dniu 2015-03-21 16:46, Gustavo A Gotelli ggotelli*|*kaliumtech.com > napisał(a): >> >> 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 >> basis >> set, >> # opt freq rb3lyp/6-311++g(d,p) pop=savemixed geom=connectivity scf=tight >> >> 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 >> data? >> > > > Hi Gustavo > Where is such a difference between theory and experiment. Around 100, 1000 > or 3000 cm-1. Or you observed it for the whole vibrational spectrum?? > >> Thanks in advance >> Gustavo-- > > https://www.youtube.com/watch?v=IGyfx3Pmeyk > Krzysztof K. Zborowski > Faculty of Chemistry > Jagiellonian University > 3 Ingardena Street > 30-060 Krakow > Poland > phone: +48(12)663-2067 > email: zborowsk()chemia.uj.edu.pl > gg 3817259 > skype kzys70 > www.chemia.uj.edu.pl/~zborowskhttp://www.ccl.net/chemistry/sub_unsub.shtmlConferences: > http://server.ccl.net/chemistry/announcements/conferences/> > From owner-chemistry@ccl.net Sat Mar 21 17:51:00 2015 From: "=?UTF-8?Q?Serdar_Bado=C4=9Flu?= serdarbadoglu=-=gmail.com" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51169-150321140912-25733-1KjQw7VC9mOo07P7Jrj21g[A]server.ccl.net> X-Original-From: =?UTF-8?Q?Serdar_Bado=C4=9Flu?= Content-Type: multipart/alternative; boundary=001a11c34ddc14c6730511d05401 Date: Sat, 21 Mar 2015 20:09:05 +0200 MIME-Version: 1.0 Sent to CCL by: =?UTF-8?Q?Serdar_Bado=C4=9Flu?= [serdarbadoglu.[*].gmail.com] --001a11c34ddc14c6730511d05401 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Dear Gustavo What type of molecule are you trying to calculate? Without knowing this I guess none of us can supply you a good answer. By the way, b3lyp/6-311++g(d,p) is a good choice for most organic heterocycles. Regards On Sat, Mar 21, 2015 at 5:46 PM, Gustavo A Gotelli ggotelli*|*kaliumtech.co= m 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 Serdar BADO=C4=9ELU, Ph.D. Gazi =C3=9Cniversitesi Fizik B=C3=B6l=C3=BCm=C3=BC --001a11c34ddc14c6730511d05401 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Dear Gustavo

What type of molecule are = you trying to calculate? Without knowing this I guess none of us can =C2=A0= supply you a good answer.

By the way,=C2=A0b3lyp/6-311++g(d,p) is a good choice = for most organic heterocycles.

Regards

On Sat, Mar 21, 2015 at 5:46 PM, Gustavo A Gotelli ggote= lli*|*kaliumtech.com <owner-ch= emistry[*]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



-=3D This is automatically added to each message by the mailing script =3D-=
E-mail to subscribers: CHEMISTRY[*]ccl.n= et or use:
=C2=A0 =C2=A0 =C2=A0 http://www.ccl.net/cgi-bin/ccl/send_ccl_message=

E-mail to administrators: CHEM= ISTRY-REQUEST[*]ccl.net or use
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Subscribe/Unsubscribe:
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Conferences: http://server.ccl.net/chemistry/announcements/co= nferences/

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=C2=A0 =C2=A0 =C2=A0 http://www.ccl.net/spammers.txt

RTFI: http://www.ccl.net/chemistry/aboutccl/instructions/





--
Serdar BADO=C4=9ELU, Ph.D.
Gazi =C3=9Cniversitesi F= izik B=C3=B6l=C3=BCm=C3=BC
--001a11c34ddc14c6730511d05401-- From owner-chemistry@ccl.net Sat Mar 21 18:26:01 2015 From: "=?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal victor ~~ fluor.quimica.uniovi.es" To: CCL Subject: CCL: problem in Gaussian 03 program Message-Id: <-51170-150321163543-10076-zaV6vzaiPKgXAPzcPTRMGg%a%server.ccl.net> X-Original-From: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal Content-disposition: inline Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-1 Date: Sat, 21 Mar 2015 21:30:50 +0100 MIME-version: 1.0 Sent to CCL by: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal [victor%%fluor.quimica.uniovi.es] On Fri, Mar 20, 2015 at 05:25:59PM -0400, Safiya Ess Amer amersaf85**yahoo.com wrote: > The geometry is not problem with my system, I use GaussView to > visualize it, that is easy but the problem about movement of two hydrogen > atoms of H2 molecule above Fe ion. I put suitable coordinates of all > atoms of the system with freezing and ran program to get energy. The > positions of H2 atoms changed manually each time. I need a way with > automaticaly changing for positions. Safiya, 1) In other words: you want a modeller that lets you decide the geometry you want to explore in your molecule. 2) You can look for tools like avogadro (once you have a geometry designed) avogadro provides you the input for g09 and other programs to compute the energy. 3) There are other modellers available, but the best option is learning a bit of programming yourself. Then you will be independent. 4) If you have the time for that you will profit quicker using a scripting languaje: python, matlab/octave, lua, ... Best regards and good luck, Dr. Víctor Luaña -- . . "The hardest part in solving a problem is recognizing / `' \ its existence. Learning the causes CAN be the road to /(o)(o)\ the solution." /`. \/ .'\ -- ¿? / '`'` \ "Lo mediocre es peor que lo bueno, pero también es peor | \'`'`/ | que lo malo, porque la mediocridad no es un grado, es una | |'`'`| | actitud" \/`'`'`'\/ -- Jorge Wasenberg, 2015 ===(((==)))==================================+========================= ! Dr.Víctor Luaña ! Mediocre is worse than ! Departamento de Química Física y Analítica ! good, but it is also ! Universidad de Oviedo, 33006-Oviedo, Spain ! worse than bad, because ! e-mail: victor++fluor.quimica.uniovi.es ! mediocrity is not a grade, ! phone: +34-985-103491 fax: +34-985-103125 ! it is an attitude +--------------------------------------------+ GroupPage : http://azufre.quimica.uniovi.es/ (being reworked) From owner-chemistry@ccl.net Sat Mar 21 19:00:01 2015 From: "Robert Molt r.molt.chemical.physics],[gmail.com" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51171-150321175651-20150-wtyylTaIwjENN9asqUvHDA###server.ccl.net> X-Original-From: Robert Molt Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=utf-8; format=flowed Date: Sat, 21 Mar 2015 17:56:44 -0400 MIME-Version: 1.0 Sent to CCL by: Robert Molt [r.molt.chemical.physics---gmail.com] Moreover, you are using the B3LYP functional. It has limited accuracy, depending on the system specifics. If it is a multi-reference problem, great care is necessary. Also note that you can only compare the TOTAL spectrum, not any one peak. On 3/21/15 5:02 PM, Wojciech Kolodziejczyk dziecial^-^icnanotox.org wrote: > Sent to CCL by: Wojciech Kolodziejczyk [dziecial(~)icnanotox.org] > It's not a gaussian thing. Did you scale it? Here is a website with > scaling factors. Find yours > http://t1.chem.umn.edu/freqscale/index.html > > 2015-03-21 14:00 GMT-05:00 zborowsk zborowsk[A]chemia.uj.edu.pl > : >> Sent to CCL by: zborowsk [zborowsk!=!chemia.uj.edu.pl] >> W dniu 2015-03-21 16:46, Gustavo A Gotelli ggotelli*|*kaliumtech.com >> napisaÅ‚(a): >>> 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 >>> basis >>> set, >>> # opt freq rb3lyp/6-311++g(d,p) pop=savemixed geom=connectivity scf=tight >>> >>> 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 >>> data? >>> >> >> Hi Gustavo >> Where is such a difference between theory and experiment. Around 100, 1000 >> or 3000 cm-1. Or you observed it for the whole vibrational spectrum?? >> >>> Thanks in advance >>> Gustavo-- >> https://www.youtube.com/watch?v=IGyfx3Pmeyk >> Krzysztof K. Zborowski >> Faculty of Chemistry >> Jagiellonian University >> 3 Ingardena Street >> 30-060 Krakow >> Poland >> phone: +48(12)663-2067 >> email: zborowsk()chemia.uj.edu.pl >> gg 3817259 >> skype kzys70 >> www.chemia.uj.edu.pl/~zborowskhttp://www.ccl.net/chemistry/sub_unsub.shtmlConferences: >> http://server.ccl.net/chemistry/announcements/conferences/> > -- Dr. Robert Molt Jr. r.molt.chemical.physics~!~gmail.com Nigel Richards Research Group Department of Chemistry & Chemical Biology Indiana University-Purdue University Indianapolis LD 326 402 N. Blackford St. Indianapolis, IN 46202 From owner-chemistry@ccl.net Sat Mar 21 19:35:01 2015 From: "Sten Nilsson Lill stenilster,gmail.com" To: CCL Subject: CCL:G: Gaussian IR frequency calculation Message-Id: <-51172-150321181613-18325-bll2bULoSeCpQ3Wc1lTwag===server.ccl.net> X-Original-From: Sten Nilsson Lill Content-Type: multipart/alternative; boundary=089e0122aec283d1470511d3c7e6 Date: Sat, 21 Mar 2015 23:16:06 +0100 MIME-Version: 1.0 Sent to CCL by: Sten Nilsson Lill [stenilster{}gmail.com] --089e0122aec283d1470511d3c7e6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Hi Gustavo, in addition to what has been suggested already, did you also do a conformational search for your system? Maybe you are not comparing the same things and therefore your difference in IR frequencies may be due to that? Also, the optimized structure may be significantly different in solvent, so you might need to invest some time in such studies as well. It again depends what you are comparing with. Hope that helps, Sten On Sat, Mar 21, 2015 at 8:37 PM, Andr=C3=A9 Farias de Moura moura_-_ufscar.= br < owner-chemistry:+:ccl.net> wrote: > 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 eve= r > 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 >> basis >> 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 peak= s. >> 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 >> >> >> >> -=3D This is automatically added to each message by the mailing script = =3D- >> E-mail to subscribers: CHEMISTRY|,|ccl.net or use:>> >> E-mail to administrators: CHEMISTRY-REQUEST|,|ccl.net or use>> >> >> > > > -- > _____________ > > 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 > --089e0122aec283d1470511d3c7e6 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi Gustavo,
in addition to what has been suggested alr= eady, did you also do a conformational search for your system? Maybe you ar= e not comparing the same things and therefore your difference in IR frequen= cies may be due to that? Also, the optimized structure may be significantly= different in solvent, so you might need to invest some time in such studie= s as well. It again depends what you are comparing with.


Hope that helps,

Sten
<= /div>

On Sat, Mar = 21, 2015 at 8:37 PM, Andr=C3=A9 Farias de Moura moura_-_ufscar.br <owner-chemistry:+:ccl.net> wrote:
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 l= evel of theory, so you need to find out if anybody has ever published a sca= ling factor for your specific choices (rb3ly= p/6-311++g(d,p)), otherwise you have to obtain the proper factor by yoursel= f. for the unrestricted case, take a look at:=C2=A0J. Phys. Chem. A,=C2=A02005,=C2= =A0109<= /span>=C2=A0(12), pp 2937=E2=80= =932941, for instance.
best

<= div>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

--089e0122aec283d1470511d3c7e6-- From owner-chemistry@ccl.net Sat Mar 21 21:22:01 2015 From: "=?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal victor^^fluor.quimica.uniovi.es" To: CCL Subject: CCL: Gaussian IR frequency calculation Message-Id: <-51173-150321212037-25808-4omVjlut3nu/uskr6evWtA,+,server.ccl.net> X-Original-From: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal Content-disposition: inline Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-1 Date: Sun, 22 Mar 2015 02:15:44 +0100 MIME-version: 1.0 Sent to CCL by: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal [victor]|[fluor.quimica.uniovi.es] On Sat, Mar 21, 2015 at 05:56:44PM -0400, Robert Molt r.molt.chemical.physics],[gmail.com wrote: > > Sent to CCL by: Robert Molt [r.molt.chemical.physics---gmail.com] > Moreover, you are using the B3LYP functional. It has limited accuracy, > depending on the system specifics. If it is a multi-reference problem, > great care is necessary. > > Also note that you can only compare the TOTAL spectrum, not any one peak. Robert, 1) Let me take your highly correct advise to remember to the newest generations that the role on computational chemistry is not being able to reproduce the number of the experiment. 2) The experiment helps in modulating our calculations, and the final objective is a perfect reprodution of the experiment. 3) But the reason is not substituting experiments. The reason is that in the processs of mimicking it we learn the rules that govern Nature. 4) There are too many questions in this forum that tend to ignore this rule and it is important to remember it again and again. Best regards, Dr. Víctor Luaña -- . . "The hardest part in solving a problem is recognizing / `' \ its existence. Learning the causes CAN be the road to /(o)(o)\ the solution." /`. \/ .'\ -- ¿? / '`'` \ "Lo mediocre es peor que lo bueno, pero también es peor | \'`'`/ | que lo malo, porque la mediocridad no es un grado, es una | |'`'`| | actitud" \/`'`'`'\/ -- Jorge Wasenberg, 2015 ===(((==)))==================================+========================= ! Dr.Víctor Luaña ! Mediocre is worse than ! Departamento de Química Física y Analítica ! good, but it is also ! Universidad de Oviedo, 33006-Oviedo, Spain ! worse than bad, because ! e-mail: victor^^fluor.quimica.uniovi.es ! mediocrity is not a grade, ! phone: +34-985-103491 fax: +34-985-103125 ! it is an attitude +--------------------------------------------+ GroupPage : http://azufre.quimica.uniovi.es/ (being reworked)