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Re: Clarification about basis sets and ECPs

Masoud Nahali

Dear Luca

about all-electron calculation:

The behavior is not strange. All-electron calculations are always more time consuming than pseudo-potential and electron core potential calculations.  

Best Wishes

Masoud Nahali, Sharif University of Technology

On Mon Feb 7 '11 9:38pm, Luca Maidich wrote
>Dear FireFly users,
>I encountered a strange behaviour in FF 7.1.G under Ubuntu about basis sets and ECPs.

>1) ECPs - The fact is that when I use the ECPs with SBKJC basis set all goes well and the program works flawlessly (see attached file Opt-SBKJC-wECP.out) but when I remove manually the ECPs, trying to perform an all electron calculation, the programs does converge but in many more cycles even using optimized structures obtained from previous jobs (see attached file Opt-SBKJC-woECP.out). Does this depend on the more electrons taken into consideration? Is there a quantitative relationship between the number of electrons considered and the number of SCF cycles?

>2) Basis sets - I also tried to perform calculation using basis sets obtained from the Downloads section and I found that the program is considerably slower, does this depend on the non optimal integration of other basis sets (in particular I tried Ahlrichs def2) or depends on other factors?

>Many thanks in advance for the help/comments
>Best Regards
>Luca Maidich

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