Hello!

To add the ECP to the particular atom in GAUSSIAN0X (X= 3 or 9), as addition to the basis set which will describe the valence electrons (first part of the the aug-cc-pVXZ-PP in EMLS called by the GEN keyword) you have to add the keyword "Pseudo=read" and write the particular ECP (as the 'identifier word, for instance LanL2DZ, or explicitly in the appropriated format as the EMLS - see http://www.nd.edu/~wschnei1/Courses/CBE_547/g03_man/g_ur/k_pseudo.htm or the GAUSSIAN09 manual-).

In the EMLS basis set the ECP description starts with

I     0
I-ECP     4     28

Otherwise, despite the calculation finished without errors apparently, you will obtain wrong results...
I guess that the wrong results arise from the bad description of the atom which is supposed to take an ECP for the core eletrons.

In other words, GAUSSIAN doesn't assign the ECP to the atom if the "Pseudo=read" keywords are not present, but the calculation run...

Regards..

D.G.

From: Grant Hill jghill(0)wsu.edu <owner-chemistry_-_ccl.net>
To: "Gomez, Diego Armando " <darkego21_-_yahoo.com>
Sent: Mon, December 6, 2010 7:18:31 PM
Subject: CCL:G: problem with aug-cc-pVxZ-PP basis sets for iodine...

Sent to CCL by: Grant Hill [jghill::wsu.edu]

On 6 Dec 2010, at 17:10, Roy Jensen JensenRH _ MacEwan.ca wrote:

> Anyone have any idea why the aug-cc-pVxZ-PP basis sets do so poorly?

Yes, they're not an all electron set and from your mail I suspect that you're not using them with an ECP (the PP part of the abbreviation is pseudo-potential). I'm surprised they do as well as you report.

I can't comprehend that Gaussian won't let you specify a general basis set / ECP combo. This functionality is surely there somewhere.

HTH,

Grant

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