Subject: ESR(EPR) spectra; G-tensor calculations

From: "Adrian Radomir Jaszewski" <[email-masked]>
Date: Wed, 20 May 1998 13:07:12 GMT+2

Dear CClers,

I'm interested in application of DFT calculations in determination of the 
geometry and magnetic parameters (isotropic and anisotropic) of  organic radicals.
I know that Gaussian94 produces output called "Fermi Contact Analysis" for
each atom in the molecule.These values can be easily convert to isotropic
EPR (ESR) hyperfine coupling constants. 
In order to perform G-TENSOR calculations I used the following options in the
input:
# PROP=EFG IOp(6/17=2,6/26=4). 
There are several sections in the output:
 
**********************************************************************
            Electrostatic Properties Using The SCF Density
 **********************************************************************

              Electrostatic Properties (Atomic Units)

 -----------------------------------------------------------------
    Center     Electric         -------- Electric Field --------
               Potential          X             Y             Z
 -----------------------------------------------------------------
 -----------------------------------------------------
    Center         ---- Electric Field Gradient ----
                     XX            YY            ZZ
 -----------------------------------------------------
 -----------------------------------------------------
    Center         ---- Electric Field Gradient ----
                     XY            XZ            YZ
 -----------------------------------------------------
 -----------------------------------------------------
    Center         ---- Electric Field Gradient ----
                   ----       Eigenvalues       ----
 -----------------------------------------------------
 -----------------------------------------------------
    Center         ---- Electric Field Gradient ----
                       ( tensor representation )
                   3XX-RR        3YY-RR        3ZZ-RR
 -----------------------------------------------------
 -----------------------------------------------------
    Center         ---- Electric Field Gradient ----
                       ( tensor representation )
                   ----       Eigenvalues       ----
 -----------------------------------------------------
 
but I don't know how to comprare these calculated values with 
the anisotropic parameters derived from the experiment - EPR
(ESR) spectrum of the radical.

Could anyone direct me to the proper references and/or shed some
light into this topic?

Many Thanks

Adrian R. Jaszewski

 --------------------------------------------------------------
 \                       Adrian R. Jaszewski                   /
 \              Department of Chemistry                        /
 \                  University of Wroceaw                      /
 \       14 Joliot-Curie St., 50-383 Wroceaw, Poland           /
 \       e-mail: [email-masked]                /
 --------------------------------------------------------------