Reductive Cyclization. A Method for the Synthesis of Tricyclic Compounds Possessing a Bridgehead Nitrogen<sup>1</sup>
作者:Nelson J. Leonard、William J. Middleton
DOI:10.1021/ja01140a035
日期:1952.10
Ground state phase diagram of a spin-2 antiferromagnet on the square lattice
作者:H. Niggemann、A. Klümper、J. Zittartz
DOI:10.1007/s100510050004
日期:2000.1
We use the vertex state model approach to construct optimum ground states for a large class of quantum spin-2 antiferromagnets on the square lattice. Optimum ground states are exact ground states of the model which minimize all local interaction operators. The groundstate contains two continuous parameters and exhibits a second order phase transition from a disordered phase with exponentially decaying