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Hyperfine Coupling Tensors

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The calculation of hyperfine coupling  tensors (in vacuum or in solution) is invoked by the keyword *ESR   in the **RESPONSE   input module. Thus a complete input file for the calculation of hyperfine coupling tensors will be:

**DALTON INPUT
.RUN RESPONSE
**INTEGRALS
.FC
.SD
**WAVE FUNCTIONS
.HARTREE-FOCK
**RESPON
.TRPFLG
*ESR
.ESRCAL
.MAXIT
   30
.TRPPRP
FC Cl 01 
.TRPPRP
.
.
.

.TRPPRP
SD  01 x 
.TRPPRP
SD  01 y 
.TRPPRP
SD  01 z 
.TRPPRP
.
.
.

*END OF

This will invoke the calculation of hyperfine coupling  tensors using the Restricted-Unrestricted  methodology [46]. In this approach, the unperturbed molecular system is described with a spin-restricted MCSCF wave function, and when the perturbation - Fermi Contact  or Spin Dipole  operators - is turned on, the wave function spin relaxes and all first-order molecular properties are evaluated as the sum of the conventional average value term and a relaxation term that includes the response of the wave function to the perturbations.

The selection of a flexible atomic orbital basis set is decisive in these calculations. Dunning's cc-pVTZ or Widmark's basis sets with some functions uncontracted, and one or two sets of diffuse functions and several tight s-functions added have been shown to provide accurate hyperfine coupling tensors [47].

If more close control of the different parts of the calculation of hyperfine coupling tensors is wanted, we refer the reader to the sections describing the options available.



Kenneth Ruud
Sat Apr 5 10:26:29 MET DST 1997