Ab-initio Calculations of Electronic Densities and Electric Field Gradients in Organometallic Compounds

T. Soldner , W. Tröger, T. Butz

The study of nuclear quadrupole interactions (NQI), i.e. of the strength,  symmetry, and orientation of the electric field gradient (EFG), by time differential perturbed angular correlation (TDPAC)  yields valuable information  on the coordination sphere and dynamics of metal sites in organic macromolecules  like proteins. In order to quantify this information, theoretical ab-initio calculations of the EFG are indispensable.

The full potential linearized augmented plane wave method (LAPW) as embodied in the WIEN95 code is a well-established and accurate method for EFG calculations  in crystals.
We test the applicability of WIEN95 to isolated molecules. The following topics are  of main interest:

• influence of unit cell dimensions
• truncation effects and their influence on the EFG
• influence of crystal-like coordination to electronic properties of molecules.

Furthermore, we are interested in the variations of the EFG under bending and  stretching the molecule.

Currently, WIEN95-calculations on the following compounds are performed:

• cadmium and mercury halides (CdCl₂, HgCl₂)
• mercury tert-butyl mercaptide
• Hg(cysteine)₂.

Collaborations:

• P. Blaha, K. Schwarz
  Institute of Technical Electrochemistry, Vienna University of Technology
  Vienna, Austria