## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

** Re^2: Can not optimize geometry in MP2/aug-cc-pVDZ **
Alexander Vasyanin

avasyanin@gmail.com

Thank you, Thomas, for reply.New version of manual is very helpful, I didn't know. I've tried D5 option, but unfortunately it did not solve the problem yet: optimization still "oscilates" around the same geometry with minimal energy changes (less than 1E-6) but with quite large GMAX (not less than 1E-4). I'll wait for tomorrow.

Enabled spherical functions also increased my energy values to about 0.036 Ha. Is it ok?

Thanks in advance,

Alexander

I've tried to use D5 option.

On Mon Feb 9 '15 10:52pm, Thomas Pijper wrote

---------------------------------------------

>Dear Alexander,

>With the aug-cc-pVDZ basis one should enable spherical functions. These are enabled with

>$CONTRL D5=.T. $END

>See pages 68-69 of the manual for more details. Enabling spherical functions may reduce partial linear dependence in your basis and help in getting more accurate MP2 gradients.

>Hope this helps.

>

>

>Kind regards,

>Thom

>

>

>

>

>

>

>

>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

>> 2 E= -727.7926962929 GMAX= 0.0001120 GRMS= 0.0000170

>>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!

Tue Feb 10 '15 6:41pm

This message read **560** times