Author Topic: Different ZPE between small and big basis sets  (Read 6889 times)

quan.phung

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Different ZPE between small and big basis sets
« on: July 13, 2011, 10:49:49 PM »
Dear Turbomole user,

I'm doing some calculations on Ferrocene with DFT/B3LYP. After geometry optimization, I use aoforce to compute ZPE. I use 2 types of basis sets:
- Small: def2-TZVP on C and H; def2-QZVPP on Fe. I got ZPE=0.21 Ha.
- Big: def2-QZVPPD on both C, H and Fe atoms. I got ZPE=0.50 Ha.
As you can see that there is a big difference between two ZPEs. I think there is some problems with the big basis set result since it give totally wrong binding energy of Ferrocene. Could you please tell me what's wrong here?

Thank you.

quan.phung

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Re: Different ZPE between small and big basis sets
« Reply #1 on: July 22, 2011, 04:57:26 PM »
Dear Turbomole users,

I computed again with def2-QZVPP for all atoms and the result of ZPE is around 0.21 Ha again. I think the problem must come from the diffuse part of basis set def2-QZVPPD.

Best regards

Arnim

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Re: Different ZPE between small and big basis sets
« Reply #2 on: July 24, 2011, 01:39:54 PM »
Hi,

when I do the calculation, I get 0.17 H with the small basis set and 0.13 H with the big basis set.
Maybe you forgot to optimize the structure?

Cheers,

Arnim

quan.phung

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Re: Different ZPE between small and big basis sets
« Reply #3 on: July 24, 2011, 08:42:19 PM »
Hi Arnim,

Thank you for your reply. Yes i optimized the structure.
In fact yesterday, I did the calculation again with serial optimization and aoforce. I got 0.17 Ha for small basis set.
I don't know if this is a bug or there is problem with our computers or I did wrong. I used 2 procedures:
- Old one: geometry optimization with jobex parallel. After that compute aoforce (serial) in the same directory. I have 0.21 Ha.
- New one: geometry optimization with jobex serial and then compute aoforce (serial) in same directory. I have 0.17 Ha.
Also, total energy compute with 2 procedures are the same, except ZPE and frequencies.

Best regards,
Quan

 



Arnim

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Re: Different ZPE between small and big basis sets
« Reply #4 on: July 26, 2011, 12:54:28 PM »
Hi Quan,

the serial and the parallel version give the same results. This is assured with TURBOTEST.

I suggest you check the two aoforce output for differences. I still think, you are using wrong coordinates somehow.
Maybe your PBS submit scripts do not copy the optimized coordinates back or something like that.

Cheers,

Arnim

quan.phung

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Re: Different ZPE between small and big basis sets
« Reply #5 on: July 26, 2011, 10:58:05 PM »
Dear Arnim,

I checked both of output files. I use both Turbomole 6.2 and 6.3 but I think there is no much different between them. This is the comparison.
http://diffchecker.com/7G5m1lb

You can see that the difference start from Block Davidson iteration and Integral of ground state density.

Best regards,
Quan

Arnim

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Re: Different ZPE between small and big basis sets
« Reply #6 on: July 27, 2011, 07:47:27 PM »
Interesting. aoforce from TM 6.2 on your node20 produces inconsistent numbers.
I just run different versions on different platforms and they all gave the correct result.
Could you run TTEST on that specific computer and, if errors occur, report them to turbomole@cosmologic.de ?

Best,

Arnim