From owner-chemistry@ccl.net Mon Nov 3 16:14:00 2008 From: "John McKelvey jmmckel . gmail.com" To: CCL Subject: CCL:G: mail from Joshi Message-Id: <-38020-081103153637-28972-htAEnkSeTC6LrSGHsG67Mw{=}server.ccl.net> X-Original-From: "John McKelvey" Content-Type: multipart/alternative; boundary="----=_Part_90978_2210072.1225744577206" Date: Mon, 3 Nov 2008 15:36:17 -0500 MIME-Version: 1.0 Sent to CCL by: "John McKelvey" [jmmckel+*+gmail.com] ------=_Part_90978_2210072.1225744577206 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Perhaps things have changed, and I've forgotten that, but I know that STO-NG* basis sets put d orbitals on the Na-Cl row of the periodic table, and I thought the same was true for 3-21G*.. Am I incorrect? Also, why not try PM6/MOPAC2007 for this for a starting pass at the geometry, along with AIGOUT which prepares a GXY input geometry Z-Matrix? Cheers! John McKelvey On Mon, Nov 3, 2008 at 8:17 AM, Marcel Swart marcel.swart|*|icrea.es < owner-chemistry%x%ccl.net> wrote: > Note also the following paper, for hydrocarbons it gives good and fast > results (seconds on regular PC): > http://dx.doi.org/10.1021/ct8003222 > > *Thermochemistry of Hydrocarbons. Back to Extended H=FCckel Theory* > * > * > On Nov 3, 2008, at 10:41 AM, Kalju Kahn kalju]=3D[chem.ucsb.edu wrote: > > > Sent to CCL by: "Kalju Kahn" [kalju:+:chem.ucsb.edu] > Joshi, > > Are you sure that you need B3LYP/3-21G* geometry for this structure? > Seems like molecular mechanics with MM3 might be better suited for > optimizing a large hydrocarbon. > > If you need DFT geometry for some reason, try to freeze all dihedrals and > optimize bond distances and angles first. Small deviations of torsional > angles around single bonds is more acceptable than an unusually stretched > bond for calculation of some molecular properties. > > Kalju > > Dear CCLers; Hi > > I am optimizing a molecule having 387 atoms (only C and H atoms) which > includes neatly 16 methyl groups as substitutions in G03w, and the method > is b3lyp/3-21g*. During the optimization the Maximum Force > and=C2 RMS=C2 Forces are sometimes converging,=C2 Maximum > Displacement=C2 and=C2 RMS=C2 =C2 =C2 =C2 Displacements are not convergi= ng and the > molecules energy is oscillating. I am using=C2 following keywords in rout= e > section as > > %mem=3D1500mb > %nproc=3D4 > #p opt=3D(gdiis,maxcycle=3D200) b3lyp/3-21g* scf=3Dmaxcycle=3D500 > > Please give me suggestion > > Thanks in advance > > Joshi > > > > Add more friends to your messenger and enjoy! Go to > http://messenger.yahoo.com/invite/ > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Dr. Kalju Kahn > Department of Chemistry and Biochemistry > UC Santa Barbara, CA 93106 > > > > -=3D This is automatically added to each message by the mailing script = =3D-> the strange characters on the top line to the %x% sign. You can also> > E-mail to subscribers: CHEMISTRY%x%ccl.net or use= :> > E-mail to administrators: CHEMISTRY-REQUEST%x%ccl.netor use> > > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > dr. Marcel Swart > > ICREA researcher at > Institut de Qu=EDmica Computacional > Universitat de Girona > > Parc Cient=EDfic i Tecnol=F2gic > Edifici Jaume Casademont (despatx A-27) > Pic de Peguera 15 > 17003 Girona > Catalunya (Spain) > > tel > +34-972-183240 > fax > +34-972-183241 > e-mail > marcel.swart%x%icrea.es > marcel.swart%x%udg.edu > web > http://www.icrea.cat/Web/ScientificForm.aspx?key=3D372 > http://iqc.udg.edu/~marcel > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > > > > ------=_Part_90978_2210072.1225744577206 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Perhaps things have changed, and I've forgotten that, but I know that S= TO-NG* basis sets put d orbitals on the Na-Cl row of the periodic table, an= d I thought the same was true for 3-21G*.. Am I incorrect?

Also,&nbs= p; why not try PM6/MOPAC2007 for this for a starting pass at the geometry, = along with AIGOUT which prepares a GXY input geometry Z-Matrix?

Cheers!

John McKelvey

On Mon, = Nov 3, 2008 at 8:17 AM, Marcel Swart marcel.swart|*|icrea.es <owner-chemistry%x%ccl.net> wrote:
Note also the following paper, for hydrocarbons it gives good and fast resu= lts (seconds on regular PC):




chem.ucsb.edu]
Joshi,

Are you sure that you need= B3LYP/3-21G* geometry for this structure? 
Seems like molecular mechanics with MM3 might be better suited for
optimizing a large hydrocarbon.

If y= ou need DFT geometry for some reason, try to freeze all dihedrals and
optimize bond distances and angles first.=   Small deviations of torsional
bond for calculation of some molecular properti= es.

Kalju
=
Dear CCLers; Hi

I am optimizing a molecule havi= ng 387 atoms (only C and H atoms) which
includes neatly 16 methyl groups as substitutio= ns in G03w, and the method
is b3lyp/3-21g*= . During the optimization the Maximum Force
and=C2 RMS=C2 Forces are sometimes converging,=C2 Maximum
Displacement=C2 and=C2 RMS=C2 = ;=C2 =C2 =C2  Displacements are not converging and the
=
molecules energy is oscillating. I am using=C2&= nbsp;following keywords in route
section as

= %mem=3D1500mb
%nproc=3D4
#p opt=3D(gdiis,maxcycle=3D200) b3lyp/3-21g* scf=3Dmaxcycle=3D500

Please give me suggestion

Thanks in advance

Joshi



      Add more friends to yo= ur messenger and enjoy! Go to


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Kalju Kahn
Department of Chemistry and= Biochemistry
UC Santa Barbara, CA 93106



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To recover the email a= ddress of the author of the message, please change
the strange characters on the top line to= the %x% sign. You can also

E-mail to subscribers: CHEMISTRY%x%ccl.net= or use:



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