From owner-chemistry@ccl.net Sun Feb 15 22:15:00 2009
From: "Jonas Baltrusaitis jasius_1*|*yahoo.com" <owner-chemistry[a]server.ccl.net>
To: CCL
Subject: CCL:G: RI-MP2 fittingbasis set
Message-Id: <-38623-090215221343-23571-g5ekSJORNpPB41zw5oZ2EA[a]server.ccl.net>
X-Original-From: "Jonas  Baltrusaitis" <jasius_1##yahoo.com>
Date: Sun, 15 Feb 2009 22:13:38 -0500


Sent to CCL by: "Jonas  Baltrusaitis" [jasius_1 _ yahoo.com]
Hi,

I want to use NWChem RI-MP2 for organometallic cluster geometry optimisation+frequency calculation (in comparison with some DFT functionals), since my structures depend heavily on weak interactions. However (unless one uses Turbomole based programs), the fitting basis sets are very limited (not only in NWChem). I would need something that goes up to Xe, hence transition metals involved. I am using gaussian basis sets, such as 6-311G* in combination with pseudopotentials, such as LANL2DZ. I never quite found a good fitting basis set for RI-MP2 anywhere for these basis sets. Of course, I could download those from Turbomole website, but aren't those "optimized" for slater basis sets?

What is a good fitting basis set, for that matter? If I found any in the literature, how can I test with my method and primary basis set to evaluate if it's "good" fit? Howdo I define or quantify this goodness of fit?

thanks

Jonas Baltrusaitis
University of Iowa