ESR(EPR) spectra; G-tensor calculations



 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: adrian -AatT- wchuwr.chem.uni.wroc.pl                /
  --------------------------------------------------------------