GROUND STATE ENERGY OF DILUTE MAGNETIC ALLOYS

The ground state energy of dilute magnetic alloys as described by the s-d-exchange Hamiltonian is calculated within the Nagaoka-Suhl theory. For integral impurity spin S it is shown that for positive coupling constant γ the energy is a holomorphic function of γ. For negative coupling one obtains an additional singular contribution of the form (-1)s-1e1/γ (γ<0). As this changes sign for different integral s-values, the interpretation of the singular part as a binding energy suggested previously does no longer hold. For half integral spin the energy is a singular function for both γ>0. The singularities are not as elementary as in the case of integral spin S, but are rather related to those of the exponential integral function. In particular, for γ>0 the origin (γ=0) is a branch point. Earlier variational calculations are compared with our new results. © 1969 Springer-Verlag.