Subject: Summary: GIAO on radicals?

From: Rudolf Herrmann <rudolf.herrmann{at}physik.uni-augsburg.de>
Date: Mon, 5 Apr 2004 13:56:52 +0200

Hello,
here is my summary for the following question:

> Hello,
> I'm using Gaussian03 for calculating NMR chemical shifts. This works fine 
for 
> singlet states. Whenever I try to calculate a radical (dublet or triplet) 
the 
> calculation crashes at the same point, independent of the basis set or 
method 
> (HF or DFT). Is this a known problem? Or what could I do to get a result?
> I include an example of the final part of the output file.
> Thank you for your help.
> Yours,
> Rudolf.
>

Thanks to Pablo Victora Garcia, Chaitanya S. Wannere, Kadir Diri, and Serguei 
Patchkovskii. The main suggestion was that I might be short of disk space 
which was not the case. The problem was that I first did a geometry 
optimization and then I connected the NMR calculation with a Link1 command. 
No problem with singlets, but this doesn't work for radicals. Here Gaussian 
seems to look for something in the checkpoint file or somewhere else which is 
not there and comes up with the error message 
> Operation on file out of range.
When the first calculation is directly the GIAO then radicals run without 
problems.

Serguei Patchkovskii noted that NMR calculations require a different approach 
for closed shell and open shell molecules. The outcome of the GIAO 
calculation for radicals may therefore not be reliable.

Thank you all again

Rudolf.

-- 
Dr. Rudolf Herrmann
Institute of Physics, University of Augsburg
Universitdtsstr. 1
D-86135 Augsburg (Germany)
e-mail: rudolf.herrmann{at}physik.uni-augsburg.de