Firefly and PC GAMESS-related discussion club


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



Re^5: Relativistic and non-relativistic basis sets.

Thomas Pijper
thomaspijper@hotmail.com


Dear Pavel,

I see. Well, the difference between cc-pVTZ and cc-pVDZ is indeed smaller. It might work, but to be honest, I do not have any experience with this particular combination, so I am not the best person to ask. Perhaps someone else on the forums has experience with this combination?


Kind regards,
Thoms


On Thu Feb 6 '14 6:58pm, Pavlo Solntsev wrote
---------------------------------------------
>Dear Thomas.
>
>
>Thanks for you feedback. My goal is to do MCSCF/XMCQDPT and spin-orbit coupling. I was planing to use contracted ANO-RCC for Cu and smaller basis set for another atoms. Is it ok if i us cc-pVTZ for Cu and cc-pVDZ for all other atoms? A difference between these basis sets is not so large, i believe.

>Pavel.
>
>
>
>On Wed Feb 5 '14 10:57pm, Thomas Pijper wrote
>---------------------------------------------
>>Dear Pavlo,

>>ANO-RCC is much, much larger than cc-pVDZ, so I would say that a mixed ANO-RCC / cc-pVDZ set is very unbalanced. I personally would distrust any results obtained this way.

>>Though I do not know what you want to calculate, I would generally recommend to use a pseudopotential if you would like to consider relativistic effects somewhat. The cc-pVXZ-PP sets by Peterson are available for copper and can be used in combination with the normal cc-pVXZ sets for lighter elements.
>>
>>
>>Kind regards,
>>Thom
>>
>>
>>
>>On Wed Feb 5 '14 8:46pm, Pavlo Solntsev wrote
>>---------------------------------------------
>>>Dear Thomas.

>>>Basically, i have two basis sets: GC ANO-RCC and cc-pVDZ. The heaviest element is copper. I don't expect high relativistic effects from copper. I would like to use the contracted ANO-RCC for Cu and the contracted cc-pVDZ for all other elements. I was wondering about possibility to mix these basis sets. This is not a technical issue, but more methodological.
>>>Thanks for any comments.

>>>Pavel.
>>>
>>>
>>>
>>>
>>>On Wed Feb 5 '14 1:50pm, Thomas Pijper wrote
>>>--------------------------------------------
>>>>Dear Pavlo,

>>>>Technically, there is no problem in combining two basis sets in one input file. However, I do not see why you would use a relativistic basis set in Firefly as it is not capable of relativistic calculations such as Douglas–Kroll–Hess or Dyall's Modified Dirac. Also, I would be cautious when mixing basis sets of considerably different qualities (such as using an unpolarized DZ set with a heavily polarized TZ set).

>>>>Could you perhaps explain your question a bit more?
>>>>
>>>>
>>>>Kind regards,
>>>>Thom
>>>>
>>>>
>>>>
>>>>
>>>>On Mon Feb 3 '14 9:01pm, Pavlo Solntsev wrote
>>>>---------------------------------------------
>>>>>Dear Alex.

>>>>>I was asked about possibility to use relativistic and non-relativistic basis sets in FF. I mean, is it ok if we combine two different basis sets in one input file?

>>>>>Thanks.
>>>>>


[ Previous ] [ Next ] [ Index ]           Fri Feb 7 '14 2:01am
[ Reply ] [ Edit ] [ Delete ]           This message read 854 times