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The consequences of a simple, phenomenological, theory of lattice thermal conductivity with respect to the effect of point imperfections are summarized. The experimental results of Berman et al. on the effect of varying the concentration of Li 6 on the conductivity of lithium fluoride are analyzed in detail.1 Rev. 95, 954 (1954). At low temperatures, considering normal three-phonon scattering processes, the relaxation times must obey r -1^a >«r 5_~« . 8 The ordinary theory of Umklapp processes would give BT 3 e~6 ,aT , where 0 is the Debye temperature and a is a constant characteristic of the vibrational spectrum. P. G. Klemens, in

This work is a generalization of the Hohenberg-Kohn-Sham theory of the inhomogeneous electron gas, with emphasis on spin effects. An argument based on quantum electrodynamics is used to express the ground-state energy of a system of interacting electrons as a functional of the current density. Expressions are derived for coefficients appearing in an expansion of the correlation functional in terms of the linear-response functions of the homogeneous system, for a gas of almost constant four-current density. The current density contains a spin-dependent term which leads, in the nonrelativistic limit, to a local potential which is also spin dependent.This potential is applied to the problems of spin splitting of energy bands in ferromagnets and spin-density-wave antiferromagnets.The relations between the present approach, that of Slater, and the collective electron theory of ferromagnetism of Stoner are described.

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