Dear ADF list,

I'm working on various complexes of UO2++ in water. When I optimize
the geometry of a UO2(H2O)4+2 cluster with no solvation field, I get
U-O bond lengths
(1.78 and 2.42 Å) in very good agreement with experiment (EXAFS).
When I include solvation via

SOLVATION
    Solvent epsilon=78.8 radius=1.4
    SurfaceType esurf
    DivisionLevel ND=3 min=0.5 Ofac=0.8
    ChargeUpdate Method=Gauss-Seidel
    DiscAttributes SCale=0.01 LEGendre=10 TOLerance=1.0d-2
    SCF PERT
    C-Matrix Exact
    Radii
      U=1.0
      O=1.52
      H 1.08
    Subend
END

the U-O bond lengths increase dramatically (from 1.78 to 1.9) and the
U-OH2 increase from 2.4 to 2.8 Å. Does anyone have any guess as to
what might be going wrong?
I'm using ZORA treatment of relativistic effects and the ZORA
compatible TZP basis set. The starting cluster geometry is two axial
O at 1.8 Å and 4 equatorial H2O at 2.5 Å.

Dave Sherman
______________
David M. Sherman
Professor of Geochemistry
Department of Earth Sciences
University of Bristol
Bristol BS8 1RJ UNITED KINGDOM
Phone: 44-(0)117-954-5446
http://mineral.gly.bris.ac.uk
Received on 2006-03-01 11:23:02