Subject: Re: CCL:ECPs for Br

From: Marcel Swart <[email-masked]>
Date: Fri, 22 Oct 1999 08:58:55 +0200

>Dr. Swart,
>
>In you reply to Jen about ECP for Br, you mentioned that some ECP uses
>r-squared form.  Is that particularly bad thing or good thing? If you have
>time, could you please shed some light on this for me? Thanks for
>your hlep.
>
>Best regards!
>
>Huajun

Dear Huajun,

this difference between the nodeless and r-powered ECP's is not important,
provided that the parameter determination is well done. With the nodeless
ECP's there could be a difference between ECP and all-electron
calculations, but this is just in absolute energies. Since we are
interested only in relative energies (i.e. wrt. the atoms separated at
infinity or so) or molecular properties, where this difference does not
show up, it doesn't matter.

Like I said before, nodeless or non-nodeless is not the issue, the quality
of the ECP parameters are. For Br and I (and other heavy atoms), I would
recommend the Stuttgart ECP's.

Best wishes,

Marcel.

=========================================
drs. Marcel Swart

Theoretical Chemistry (MSC)
Molecular Dynamics (GBB)

Rijksuniversiteit Groningen
Chemistry Department
Nijenborgh 4
9747 AG Groningen
The Netherlands

tel : +31 - (0)50 - 3634377
fax : +31 - (0)50 - 3634441

E-mail : [email-masked]
WWW: http://hydra.chem.rug.nl/~swart/
=========================================