On Tue, Nov 4,
2008 at 6:18 PM, Orlin Blajiev blajiev()
vub.ac.be <owner-chemistry- -ccl.net> wrote:
Sent to CCL by: Orlin Blajiev [blajiev^^vub.ac.be]
Hi again,
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
frequency calculation.
Thanks very much in advance.
Orlin
>
>Sent to CCL by: "Kalju Kahn" [kalju+/-chem.ucsb.edu]
>Orlin,
>
>If you loosen these criteria too much, you will have a successful
>calculation but the structure found will be too far from the true
minimum.
> Being able to do a calculation is not the same thing as being able to
get
>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
in:
>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
have
>negative frequencies. After the frequency calculation, it will not
hurt
>to try Opt=ReadFC, Geom=Check; you might find a better structure quickly
>using the correct Hessian.
>
>Kalju
>
>>
>> Sent to CCL by: Orlin Blajiev [blajiev%x%vub.ac.be]
>> Hi,
>>
>> I will appreciate an advise how to relax Maximum Displacement
condition
>> (or neglect it althogether). I am already using IOP(1/7=1200).
>>
>> Maximum Force 0.000275
0.001800 YES
>> RMS Force
0.000063 0.001200 YES
>> Maximum Displacement 0.125614
0.007200 NO
>> RMS Displacement 0.017703
0.004800 NO
>>
>> Thank in advance.
>>
>> Orlin
>>
>> 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>
>
>
>
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
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