Firefly and PC GAMESS-related discussion club


 
Learn how to ask questions correctly  
 
 
We are NATO-free zone
 



Re^2: Problems with hessian

Alex Granovsky
gran@classic.chem.msu.su


Dear Guilherme,

as to the message itself:

>>THIS IS NOT A STATIONARY POINT ON THE MOLECULAR PES *
>>*     THE VIBRATIONAL ANALYSIS IS NOT VALID !!!

it usually means that opttol in statpt is not tight enough
to make vibrational analysis code happy.

See:

http://classic.chem.msu.su/cgi-bin/ceilidh.exe/gran/gamess/forum/?C34df668afbHW-7264-875+00.htm

for additional details on this message.

While this message can be ignored in most cases, you may consider
to refine the structure by running another optimize job using tighter
opttol (say 1.0d-5 or so) and starting with already optimized
structure. It is also good idea to provide already computed hessian
as a starting guess. This will converge in just a few iterations.

Kind regards,
Alex Granovsky




On Sat Nov 30 '13 11:25pm, Masoud Nahali wrote
----------------------------------------------
>>
>
>Dear Guilherme

>Is one of the frequencies too small ? If so please double the number of displacements in each direction to see whether the smaller frequency disappears or not. You can apply it using $FORCE NVIB=2 $END. Then please let us know whether it improves the results. If the issue doesn't fit the proposed solution please let us see the output file.

>Sincerely Yours, m
>
>
>-------------
>Masoud Nahali
>SUT
>
>
>
>
>
>On Sat Nov 30 '13 10:47pm, guilherme wrote
>------------------------------------------
>>Hi guys,

>>I have a problem with the calculate of the hessian. I cannot achieve the correct conformation of my transition state. The calculate ends "normally" but it shows the message:

>>THIS IS NOT A STATIONARY POINT ON THE MOLECULAR PES *
>>*     THE VIBRATIONAL ANALYSIS IS NOT VALID !!!

>>and in the result I had to find just one negative frequency but in this case found 2 negative frequencies.  
>>
>>
>>My input is:

>> $contrl runtyp=hessian coord=zmt nzvar=  39 $end
>> $basis  gbasis=N311 ngauss=6 ndfunc=1 npfunc=1 nffunc=1 $end
>> $contrl icut=11 itol=30 maxit=5000 $end
>> $statpt hssend=.t. nstep=1000 dxmax=0.1 trupd=.f. $end
>> $data

>>I've already tried to freeze the important bonds but didn't work too.

>>Please guys, does someone have an idea?
>>

[ This message was edited on Sun Dec 1 '13 at 1:09am by the author ]


[ Previous ] [ Next ] [ Index ]           Sun Dec 1 '13 1:09am
[ Reply ] [ Edit ] [ Delete ]           This message read 774 times