"Jamin Krinsky jamink(a)berkeley.edu" wrote:
Sent to CCL by: Jamin Krinsky [jamink,+,berkeley.edu]
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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
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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>
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<br>
</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>
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