From owner-chemistry@ccl.net Fri Jan  6 11:27:01 2012
From: "Benjamin Stein benjamin.w.stein#,#gmail.com" <owner-chemistry^_^server.ccl.net>
To: CCL
Subject: CCL:G: Natural Resonance Theory Calculations
Message-Id: <-46120-120106112602-30643-Z3YsMKx9al9LrbT6vUfupQ^_^server.ccl.net>
X-Original-From: Benjamin Stein <benjamin.w.stein~!~gmail.com>
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Date: Fri, 6 Jan 2012 09:25:50 -0700
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Sent to CCL by: Benjamin Stein [benjamin.w.stein],[gmail.com]

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Hi Italo,

Unfortunately the NRT sometimes has a little trouble getting started. =
You can manually enter reference structures using the NRTSTR keyword; =
enter at least the parent NBO structure, and then maybe structures =
formed by a few leading delocalizations. If they were bad choices the =
NRT routine will let you know about secondary structures having higher =
weights than primary structures.

-Ben



On Jan 5, 2012, at 4:13 PM, Italo Anjos italocurvelo^gmail.com wrote:

> Hello,
>=20
> I' ve been running some NRT (Natural Resonance Theory) calculations =
using NBO 5.9/ Gaussian g09. For most compounds, analysis seem to be =
successful as they find many canonical structures and display their =
respective weightings. But for a few molecules, NBO seems unable to =
determine the resonance structures and output displays the following =
message:
>=20
> No covalent reference structures found; abandon NRT analysis
>=20
> All calculations were made for a set of sulphur-containing =
heterocyclic compounds. It seems odd that for some of them, NBO found =
dozens of canonical structures and it found none for the others.
>=20
> Could anyone help me with this problem?
>=20
> I appreciate any help.
>=20
> Regards,
>=20
> Italo


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<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi =
Italo,<div><br></div><div>Unfortunately the NRT sometimes has a little =
trouble getting started. You can manually enter reference structures =
using the NRTSTR keyword; enter at least the parent NBO structure, and =
then maybe structures formed by a few leading delocalizations. If they =
were bad choices the NRT routine will let you know about secondary =
structures having higher weights than primary =
structures.</div><div><br></div><div>-Ben</div><div><br></div><div><br></d=
iv><div><br><div><div>On Jan 5, 2012, at 4:13 PM, Italo Anjos =
italocurvelo^gmail.com wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote =
type=3D"cite">Hello,<div><br></div><div>I' ve been running some NRT =
(Natural Resonance Theory) calculations using NBO 5.9/ Gaussian g09. For =
most compounds, analysis seem to be successful as they find many =
canonical structures and display their respective weightings. But for a =
few molecules, NBO seems unable to determine the resonance structures =
and output displays the following message:</div>
<div><br></div><div><i>No covalent reference structures found; abandon =
NRT analysis</i></div><div><br></div><div>All calculations were made for =
a set of sulphur-containing heterocyclic compounds. It seems odd that =
for some of them, NBO found dozens of canonical structures and it found =
none for the others.</div>
<div><br></div><div>Could anyone help me with this =
problem?</div><div><br></div><div>I appreciate any =
help.</div><div><br></div><div>Regards,</div><div><br></div><div>Italo</di=
v>
</blockquote></div><br></div></body></html>=

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