On the calculation of G tensors of organic radicals

The results of calculations of doublet state G tensors of organic radicals often show unsatisfactory agreement with the respective experimental data. This led us to reconsider the results of the Rayleigh–Schrödinger perturbation theory approach found in the literature. We came to the conclusion that neither the expressions given for restricted nor for unrestricted Hartree–Fock functions are fully correct. In this paper new expressions for the G tensor to be used with restricted Hartree–Fock functions will be introduced and results of calculations employing these new formulas in conjunction with molecular states from semiempirical Hartree–Fock-type calculations are discussed.