CCL:G: Problem in preparing a proper input geometry for ONIOM calculations



Hi Krati Joshi,
    It would be helpful if you have provided at least a part of the output file to look into the matter. But most probably during ONIOM calculations, in gaussian it uses additional internal coordinates, to aid the optimization.
    What I am guessing is one of those values might have come closer to the maximum value,
eg: angle coming closer to 180.

so you may want to look at the angle/dihedral/distance which has an unreasonable value and can ask the program not to consider it, using the modredundent keyword. (more infor can be found in the webpage)

hope it helps.

Neranjan
  

On Mon, Jul 25, 2011 at 9:45 AM, Gkourmpis, Thomas Thomas.Gkourmpis++borealisgroup.com <owner-chemistry^ccl.net> wrote:

Sent to CCL by: "Gkourmpis, Thomas" [Thomas.Gkourmpis_._borealisgroup.com]
Joshi Hi

The most common error people do when they're preparing ONIOM structures is either in the definition of the High and low level structures or in the connecting point between them. In Gaussian the program connects the two sections (high and low) via a dummy atom/bond (hydrogen). This atom has to be connected only to one atom and not more as the system cannot deal with it.

I'm sorry I cannot be of more use to you but you don't really provide any information on how you're building the structure. Anyhow I would recommend you go through the review papers on the method by the relevant group that developed it as they're very good and they explain in detail how the method works.

Hope it helps
Thomas

-----Original Message-----
> From: owner-chemistry+thomas.gkourmpis==borealisgroup.com:+:http://ccl.net" target="_blank">ccl.net [mailto:owner-chemistry+thomas.gkourmpis==borealisgroup.com:+:ccl.net] On Behalf Of Krati Joshi kjjulie.joshia/gmail.com
Sent: Monday, July 25, 2011 12:38 PM
To: Gkourmpis, Thomas
Subject: CCL: Problem in preparing a proper input geometry for ONIOM calculations


Sent to CCL by: "Krati  Joshi" [kjjulie.joshi%a%gmail.com]
Dear all,
           I am working on Gausian 03 from last few months. Write
now i am working on ONIOM calculations but i am facing a serious
problem in it.Whenever i submit  a job, it crashes after some time with
an error message "Error in internal coordinates". It shows that there
is some problem in my input geometry therefor i tried several times with
different geometries but still i am not able to fix the problem.so pls  suggest me if anybody knows how to prepare a proper input goemetry for ONIOM calculations.It will be of great help to me.
Thanking You
Krati Joshi
Catalysis Division National Chemical laboratry,Dr. Homi Bhaba road Pune, India.
Email,kjjulie.joshi-at-gmail.comhttp-:-//www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp://www.ccl.net/chemistry/sub_unsub.shtmlhttp://www.ccl.net/spammers.txtThis Email and any files transmitted with it are confidential and
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--
Neranjan Perera
Graduate Student