Instability of the uniform antiferromagnetic chain. II. Heisenberg interaction in the Hartreehyphen;Fock approximation

摘要

We consider a linear antiferromagnetic chain of elastically coupled spins in the Hartreehyphen;Fock approximation to the Heisenberg Hamiltonian. The nuclear dynamics is neglected. The instability of the system is investigated and the results are compared with the Xhyphen;Y model treated in I. It is shown that the Hartreehyphen;Fock approximation is essentially equivalent to a renormalization of the exchange integral in the Xhyphen;Y model.