From CUNDARIT : at : MEMSTVX1.bitnet  Thu Oct 29 12:34:00 1992
Date: Thu, 29 Oct 92 17:34 CDT
From: CUNDARIT%MEMSTVX1.BITNET { *at * } OHSTVMA.ACS.OHIO-STATE.EDU
Subject: More TM calcs.
To: chemistry at.at ccl.net


Concerning TM calcs,

        I'd like to follow up on Thersa Windus' comments on transition
metal calcs.  We've probably used GAMESS (Iowa State version) as extensively
for transition metals as anyone else and from our point of view the big
benefit to GAMESS is the built-in ECPs from Walt Stevens and co., the so-called
SBKJs (Can. J. Chem. 1992, 70, 612).  We have had quite good success in
predicting geometries, rotational barriers, reaction barriers and the like
using the SBKJs, which are formally triple-zeta for the "valence" nd, (n+1)s and
(n+1)p.  They also include the (n-1)s and (n-1)p outer core which the concensus
seems to indicate are essential.  To my knowledge, the SBKJ for the s- and
p-block elements are built in Gaussian, but not for the d-block although they
can be entered manually.  Now that the SBKJs have been published I encourage
anyone interested in getting into TM-containing systems to give them a whirl in
their favorite program.
        Folks have, of course, have taken the basic Hay-Wadt scheme and
augmented the basis sets and done some excellent TM work; the research of
Morokuma, Hall and their collaborators come to my mind, but undoubtedly there
are others.  The work of Gernot Frenking is the first methodical analysis that
I have seen of the various core size and basis set augmentation schemes for
the Hay-Wadt.  I highly recommend Gernot's article to anyone planning on
getting into TM calcs.
        There are also the ECP schemes of Ross, Ermler, Pitzer, et al.; if my
understanding is correct, this group has now extended their scheme to the
entire Periodic Table!  Doesn't CADPAC include Huzinaga's model potentials
for the d-block?  Preuss and company have published ECP schemes for the
lanthanides, and we have extended the SBKJ scheme to the lanthanides.  Thus,
the ECP options in ab-initio calcs. are rapidly growing, definitely worth a
look for anyone interested in the nether regions of the Periodic Table.


                                        Tom Cundari
                                        Assistant Professor
                                        Department of Chemistry
                                        Memphis State University
                                        Memphis, TN 38152