Subject: Relatistic effects in Gaussian calculations

From: Kim Bolton <[email-masked]>
Date: Mon, 14 Aug 2000 12:00:29 +0200 (MDT)

Dear CClers,

I have received a question from a colleague, and wondered if any of you 
know the answer(s).  It may be best if you reply directly to him 
([email-masked]).

Many thanks,
Kim
 ------------------------------------------------------
Hi Kim,

All my future research exclusively deals with superheavy elements,
particularly transactinides (Z>103). I've been working in that field
partially but I considered only small molecules (M-tetrachlorides,
M-oxychlorides and -halides, M: E104,E105,E106,E107). Within my
four-component DFT code I could calculate binding energies and the geometries
of such species.  However, the accuracy is not sufficient enough (I'd say for
the binding energies 0.2-0.4 eV, but the geometries are quite good reproduced
compared to the experiment). Usually we can predict the trends of the
physico-chemical properties (enthalpies, volatilities,..) of these superheavy
elements correctly compared to their homologues in the periodic table by
analyzing the overlap integrals and a population analysis, which means that
the predictions are made indirectly. 

Now we want to extend the research: 

 1) stability of big complexes in solutions (hydrolysis,
    solution effects,...)
 2) smaller molecules in the gas-phase (e.g. [E108]O_4):
    polarizabilities, van-der-Waals coefficients, adsorption on
    surfaces
 3) reaction paths for chemical reactions of small molecules
 4) reaction rate coefficients

I guess there is no universal computer code which includes all these
points. I know that GAUSSIAN is very good for electronic and geometric
structures but I doubt that it can handle spin-orbit effects properly.
Furthermore, are there basis sets for heavy elements? How good is the
relativistic Pseudopotential? 

Thank you,
Sven

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Dr. Sven Varga                           phone: +46 31-772 3675
Chalmers University of Technology        Fax  : +46 31-772 3496
Department of Experimental Physics       email: [email-masked]
S-41296 Göteborg                         wwweb: http://fy.chalmers.se/f3c/
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