Iii. Solid State Physics

The well known phenomenological theory of F. and H. London leads to rather severe restrictions for the electronic wave functions which might possibly account for the phenomenon of superconductivity. Yet all attempts to construct such wave functions according to the principle of quantum mechanics have been so far unsuccessful. This failure seems to stem from the use of one-electron functions for a problem for which the electronic interaction is of great importance. It was generally assumed that the many electron wave functions are too difficult to handle. Actually, the Bloch-Slater theory of ferromagnetism required the use of many electron functions, but these were not associated with any current and thus were not appropriate for a theory of either normalor super-con-