CCL:G: Isotope
- From: "Kimikazu Sugimori"
<kimikazu.sugimori]![gmail.com>
- Subject: CCL:G: Isotope
- Date: Thu, 11 Mar 2010 06:56:52 -0500
Sent to CCL by: "Kimikazu Sugimori" [kimikazu.sugimori()gmail.com]
Hi Jamin,
I think it's true the Born-Oppenheimer approx. based calculation can only know
same equilibrium geometry of the isotopomer.
So we should solve Schroedinger equation without BO or obtain the solution
(eigen values and functions) from the anharmonic potential.
Wavepacket dynamics, classical trajectory, ab initio or Car-Parrinello MD,
or anharmonic correction for normal mode (harmonic oscillator) analysis
are alternatives for vibrationally averaged properties.
Kimikazu
--
Kimikazu SUGIMORI, Ph.D
Kinjo University
> "Jamin Krinsky jamink(a)berkeley.edu" wrote:
>
> Sent to CCL by: Jamin Krinsky [jamink,+,berkeley.edu]
> --0016362842429aeccd048176246e
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>
> Hi Prasenjit,
> In a normal ab initio calculation (DFT, etc.) you are assuming the
> Born-Oppenheimer approximation that the nuclei are not moving, so you are
> going to get the same geometry for H and D substitution. What will change
> with isotope are frequency-dependent properties: zero point energies, etc.
> The reason why X-D bonds are shorter than X-H bonds is that the lowest
> vibrational level of X-D is lower than that for X-H, so it sits closer two
> the equilibrium geometry at the BOTTOM of an anharmonic potential well. I
> think you'd have to solve a frequency-coupled nuclear Schrodinger equation
> to get that behavior in a geometry optimization. Please someone correct me
> if I'm wrong.
> Regards,
> Jamin
>
>
> On Tue, Mar 9, 2010 at 9:59 AM, Prasenjit SEAL prasenjit.seal|,|
> crm2.uhp-nancy.fr <owner-chemistry-*-ccl.net> wrote:
>
> >
> > Sent to CCL by: Prasenjit SEAL [prasenjit.seal##crm2.uhp-nancy.fr]
> > Hi CCL subscribers,
> >
> > Can anybody tell me which software can perform optimization of
isotopes? I
> > want to perform a geometry optimization of D2 and HD molecules.
> >
> > If it is Gaussian or MOLPRO, then how I should proceed?
> >
> > Thanks in advance.
> >
> > Cheers,
> > PShttp://www.ccl.net/chemistry/sub_unsub.shtmlConferences:
> > http://server.ccl.net/chemistry/announcements/conferences/>;
> >
> >
>
>
> --
> Jamin L Krinsky, Ph.D.
> Molecular Graphics and Computation Facility
> 175 Tan Hall, University of California, Berkeley, CA 94720
> jamink-*-berkeley.edu, 510-643-0616
> http://glab.cchem.berkeley.edu
>
> --0016362842429aeccd048176246e
> Content-Type: text/html; charset=ISO-8859-1
> Content-Transfer-Encoding: quoted-printable
>
> Hi Prasenjit,<br>In a normal ab initio calculation (DFT, etc.) you
are assu=
> ming the Born-Oppenheimer approximation that the nuclei are not moving, so
=
> you are going to get the same geometry for H and D substitution. What will
=
> change with isotope are frequency-dependent properties: zero point
energies=
> , etc. The reason why X-D bonds are shorter than X-H bonds is that the
lowe=
> st vibrational level of X-D is lower than that for X-H, so it sits closer
t=
> wo the equilibrium geometry at the BOTTOM of an anharmonic potential well.
=
> I think you'd have to solve a frequency-coupled nuclear Schrodinger
equ=
> ation to get that behavior in a geometry optimization. Please someone
corre=
> ct me if I'm wrong.<br>
> Regards,<br>Jamin<br><br><br><div
class=3D"gmail_quote">On Tue, Mar 9, 2010=
> at 9:59 AM, Prasenjit SEAL prasenjit.seal|,|<a href=3D"http://crm2.uhp-nan=
> cy.fr">crm2.uhp-nancy.fr</a> <span
dir=3D"ltr"><<a href=3D"mailto:owner-=
>
chemistry-*-ccl.net">owner-chemistry-*-ccl.net</a>></span>
wrote:<br>
> <blockquote class=3D"gmail_quote" style=3D"margin: 0pt
0pt 0pt 0.8ex; borde=
> r-left: 1px solid rgb(204, 204, 204); padding-left:
1ex;"><br>
> Sent to CCL by: Prasenjit SEAL [prasenjit.seal##<a href=3D"http://crm2.uhp-=
> nancy.fr"
target=3D"_blank">crm2.uhp-nancy.fr</a>]<br>
> Hi CCL subscribers,<br>
> <br>
> Can anybody tell me which software can perform optimization of isotopes? I
=
> want to perform a geometry optimization of D2 and HD molecules.<br>
> <br>
> If it is Gaussian or MOLPRO, then how I should proceed?<br>
> <br>
> Thanks in advance.<br>
> <br>
> Cheers,<br>
> PS<br>
> <br>
> <br>
> <br>
> -=3D This is automatically added to each message by the mailing script
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> </blockquote></div><br><br
clear=3D"all"><br>-- <br>Jamin L Krinsky, Ph.D.<=
> br>Molecular Graphics and Computation Facility<br>175 Tan Hall,
University =
> of California, Berkeley, CA 94720<br><a href=3D"mailto:jamink-*-berkeley.edu"=
> >jamink-*-berkeley.edu</a>, 510-643-0616<br>
> <a href=3D"http://glab.cchem.berkeley.edu">http-:-//glab.cchem.berkeley.edu</=
> a><br><br>
>
> --0016362842429aeccd048176246e--
>
>