H. Asakawa et M. Suzuki, APPLICATION OF A NOVEL CLUSTER-EFFECTIVE-FIELD THEORY TO THE 3-DIMENSIONAL HUBBARD-MODEL, Physica. B, Condensed matter, 212(2), 1995, pp. 149-157
A scheme for evaluating the critical point of a phase transition in th
e Hubbard model is formulated on the basis of the quantum-effective-fi
eld theory and the super-effective-held theory. The phase diagrams obt
ained by the present scheme are shown.