Magnetic Properties of Hydrogen Fluoride. II. Susceptibility

摘要

A method is outlined for the calculation of the magnetic susceptibility khgr; from the groundhyphen;state wave function of1Sgr; molecules. The diamagnetic contribution khgr;dis obtained directly by firsthyphen;order perturbation theory and the paramagnetic contribution khgr;pis determined by a variational technique based on minimizing the secondhyphen;order energy in an external magnetic field. When applied to an SCFmdash;LCAOmdash;MO function for hydrogen fluoride, the theoretical result is lang;khgr;rang;Av=mdash;8.74times;10mdash;6erg gaussmdash;2molemdash;1, in excellent agreement with the experimental value of mdash;8.6times;10mdash;6erg gaussmdash;2molemdash;1. The separate contributions, with respect to the fluorine as origin, are somewhat more in error, with lang;khgr;drang;Av=mdash;9.58times;10mdash;6erg gaussmdash;2molemdash;1(exp: mdash;9.2times;10mdash;6erg gaussmdash;2molemdash;1) and lang;khgr;prang;Av=0.855times;106erg gaussmdash;2molemdash;1(exp: 0.609times;10mdash;6erg gaussmdash;2molemdash;1, as obtained from the rotational magnetic moment). For the isoelectronic atoms Fmdash;and Ne (in which there is only a diamagnetic term), analytic Hartreehyphen;Fock functions yield lang;khgr;rang;Avvalues equal to mdash;12.7times;10mdash;6erg gaussmdash;2molemdash;1(exp: sim;mdash;12times;10mdash;6) and mdash;7.48times;10mdash;6erg gaussmdash;2molemdash;1(exp: mdash;6.7 to mdash;7.7times;10mdash;6), respectively.By a comparison of the results obtained with different molecular wave functions for hydrogen fluoride (onehyphen;center and twohyphen;center approximations), the sensitivity of the magnetichyphen;susceptibility components (especially the paramagnetic terms) to the form of the wave function is clearly demonstrated. This suggests that khgr; and its components can serve as useful criteria for the accuracy of electron distributions and indicates the need for refinements in the hydrogen fluoride functions. Finally, the availability of a method for the theoretical evaluation of the susceptibility tensor components suggests that additional measurements should be done to improve the experimental values.