CCL:G: convergence-maximum displacement
- From: "John McKelvey" <jmmckel__gmail.com>
- Subject: CCL:G: convergence-maximum displacement
- Date: Wed, 5 Nov 2008 08:45:09 -0500
There may be a very serious conceptual issue here. I am curious exactly
what you are looking for. Are you just curious how to do a frequency
calculation, or are you just interested in what the resulting lower energy
vibrational modes and what the Max Disp might look like? With the Max Disp
so large it is difficult to imagine the physical significance of doing a
frequency calculation other wise.
On Tue, Nov 4,
2008 at 6:18 PM, Orlin Blajiev blajiev() vub.ac.be <owner-chemistry- -ccl.net>
Sent to CCL by: Orlin Blajiev [blajiev^^vub.ac.be]
I would like to post again the question about how to neglect the "Maximum
Displacement 0.125614 0.007200
NO" convergence option in Gaussian. I would like just to proceed to a
Thanks very much in advance.
>Sent to CCL by: "Kalju Kahn" [kalju+/-chem.ucsb.edu]
>If you loosen these criteria too much, you will have a successful
>calculation but the structure found will be too far from the true
> Being able to do a calculation is not the same thing as being able to
>the correct result.
>If you really want to neglect displacement conditions, just use the
>geometry that gave the results below (or pick a geometry with the lowest
>energy from your search).
>Your forces are small, the PES must be very flat in the region you are
>large changes in the structure will cause only small change in energy.
>You may want to make sure that your structure is a minimum, not a saddle
>point or a some plateau via frequency calculation. You should not
>negative frequencies. After the frequency calculation, it will not
>to try Opt=ReadFC, Geom=Check; you might find a better structure quickly
>using the correct Hessian.
>> Sent to CCL by: Orlin Blajiev [blajiev%x%vub.ac.be]
>> I will appreciate an advise how to relax Maximum Displacement
>> (or neglect it althogether). I am already using IOP(1/7=1200).
>> Maximum Force 0.000275
>> RMS Force
0.000063 0.001200 YES
>> Maximum Displacement 0.125614
>> RMS Displacement 0.017703
>> Thank in advance.
>> Orlin Blajiev
>> Electrochemical and Surface Engineering (SURF)
>> Faculty of Applied Science
>> Vrije Universiteit Brussel
>> Pleinlaan 2 - 1050 Brussels - Belgium
>> tel: ++32 2 6293538 - fax: ++32 2 6293200>
>Dr. Kalju Kahn
>Department of Chemistry and Biochemistry
>UC Santa Barbara, CA 93106>
Electrochemical and Surface Engineering (SURF)
Faculty of Applied Science
Vrije Universiteit Brussel
Pleinlaan 2 - 1050 Brussels - Belgium
tel: ++32 2 6293538 - fax: ++32 2 6293200
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