Subject: Electric Field Gradient.

From: Chris Wigglesworth <[email-masked]>
Date: Fri, 16 May 1997 13:41:45 +0100 (BST)

I wonder if someone could explain to me the reason for the differing EFG 
values I am obtaining from GAMESS and Gaussian94 even though I am using 
almost identical models and both programs seem to calculate the EFG in the 
same way.

My model includes a central Lithium with basis set (BS) 6-31G*, 
surrounded by six oxygens with BS 6-31+G*, the rest of the model is 
completed with atoms with a 3-21G basis set and surrounding point charges 
to make the model neutral. It is the same for both programs except that I 
believe Gaussian94 uses 5D functions by default as opposed to GAMESS 
which uses 6 and I am not sure that the default polarisation and diffuse 
function values are the same for both programs.

The principal axis frame values of the EFG tensor given by the two programs 
for this model is,

EFG              XX         YY         ZZ

GAMESS       -0.001736  -0.001732  -0.003468

Gaussian94   -0.003731  -0.003726  -0.007457

Is the large difference due to the differing polarisation parameters, or 
the diffuse function values? I wouldn't have thought that the default 
values differed enough to make this large of a difference, so is there 
another reason?

I will post a summary of any responces that I get.

Chris Wigglesworth.

Research Student
The Open University
Walton Hall
Milton Keynes
MK7 6AA

Tel:(01908) 653896
e-mail: [email-masked]

* In my final year and looking for a job! :-) *