Upper limits of magnetic anisotropy of molecule with closed electron shell

Two simple upper limits have been established for the anisotropy of magnetic susceptibility of linear molecules with closed electron shells; these can be used to estimate the top limit on magnetic anisotropy of a molecule = – if its mean magnetic susceptibility is known, without any information whatever on the electronic wave function. The first of these limits is valid for the magnetic anisotropy of the ground electronic state X¹, and the second is valid for any ¹ state, including the excited state. The application of these limits to the evaluation of magnetic anisotropy is illustrated in the examples of the molecules of CO₂, FCCF, HCCF, FCN, LiH, and the excited state of the H₂ molecule. It is shown that these limits are useful for revealing cases of internal contradictions (or error) in individual values of magnetic anisotropy, including very rough values obtained in calculations of the magnetic properties of molecules in a limited basis set.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 24, No. 2, pp. 143–149, March–April, 1988.