New Variational Method for the Antiferromagnetic Ground State

A new method is developed to treat the problem of the antiferromagnetic ground state. Starting with an approximate perturbation theory, a functional form for the ground-state wave function is found. This functional form is used as the basis for a variational calculation. The present calculation is specialized to the case of spin $\frac{1}{2}$ but can be generalized to higher spin. From this calculation the ground-state energy and spin deviation are found for several lattices. An advantage of this method is that it yields an explicit wave function for the ground-state quantities. A comparison between this method and previous techniques is also presented.