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Re^3: Can not optimize geometry in MP2/aug-cc-pVDZ

Alex Granovsky

Dear Alexander,
Dear Thom,

I'm sorry for delay with my feedback. I was waiting for CPU resources to play with this job.
I'm now investigate convergence problem and will report my findings in a couple of days.  

Kind regards,

On Wed Feb 25 '15 11:15am, Thomas Pijper wrote
>Dear Alexander,

>Thanks for the followup. Sorry to hear that further tightening of accuracy options did not help. I'm actually surprised this system gives any problems as it is seemingly quite straightforward (a stable neutral organic molecule with a geometry close to equilibrium).

>If you like, I can experiment a bit with your system though this will take some time.
>Kind regards,
>On Tue Feb 24 '15 9:22pm, Alexander Vasyanin wrote
>>Hi All!

>>I didn't solve the problem. Looks like it appears when diffusion functions added to the basis sets: with 6-311G* and cc-pVDZ it optimizes, but 6-311+G* and aug-cc-pVDZ both failed, oscillating with GMAX not less than 1E-4.
>>I think the problem is with some gradient artifacts so I also tried to set tighter values to NCONV (8) in addition to values for $MP2GRD recommended by Prof. Granovsky, but it breaks SCF convergence.

>>So I gave up...
>>On Mon Feb 9 '15 7:47pm, Alexander Vasyanin wrote
>>>Dear All,
>>>I've got a problem with geometry optimization (see attached input file). DFT methods (B3LYP, PBE0) with the same input geometry converge fine, but MP2 fails to converge showing a progress like this:

>>>$ grep 'E=' 1.dat | cat -n
>>>     1  E=     -727.7926962177  GMAX=   0.0001417  GRMS=   0.0000243

>>>I've tried to use symmetry (CS) to make calculation faster with IHREP=5 option, but it also didn't help to reach convergence even after 40 iterations.

>>>Is it possible to improve convergence (may be with some option in $MP2GRD)?

>>>Thanks in advance!

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