Firefly and PC GAMESS-related discussion club

 
Learn how to ask questions correctly  
 
 

 

Andrei V Scherbinin
andrei.scherb@gmail.com

Small-core definition implies that some outer-core shells are
also included in the calculation, while they are removed by
large-core ECP. For Ga atom as an example, a large-core ECP
removes all 28 core electrons ([Ar]3d^10), while a small-core
ECP removes only 10 [Ne].

Usually the small-core definition is more preferable - see,
e.g., the work by Peterson concerning Ga and related atoms:

K. A. Peterson, J. Chem. Phys. 119, 11099 (2003)

A compromise solution is a 18-electron ECP that removes [Ar] core
but includes the 3d^10 semicore shell in the calculation.

The corresponding ECPs and the associated AO basis sets can be
taken for free from the EMSL portal:

https://bse.pnl.gov/bse/portal


Sincerely, Andrei


On Mon Apr 16 '12 5:26pm, Vladislav Ivanistsev wrote
----------------------------------------------------
>Dear Alex,
>how can I define small core ECP?
>Could not find definition of 'small' anywhere.
>Sincerely,
>Vladislav

>On Sun Apr 1 '12 2:33am, Alex Granovsky wrote
>---------------------------------------------
>>Hi,

>>by the way, use of small core ECP is most likely preferred in modeling �this system.

>>Regards,
>>Alex Granovsky
>>