|
In statistical mechanics, the eight-vertex model is a generalisation of the ice-type (six-vertex) models; it was discussed by Sutherland,〔B. Sutherland, J. Math. Phys. 11, 3183 (1970).〕 and Fan & Wu,〔C. Fan and F. Y. Wu, Phys. Rev. B 2, 723 (1970).〕 and solved by Baxter in the zero-field case.〔R. Baxter, Phys. Rev. Letters 26, 832 (1971).〕 ==Description== As with the ice-type models, the eight-vertex model is a square lattice model, where each state is a configuration of arrows at a vertex. The allowed vertices have an even number of arrows pointing towards the vertex; these include the six inherited from the ice-type model (1-6), and sinks and sources (7, 8). We consider a lattice, with vertices and edges. Imposing periodic boundary conditions requires that the states 7 and 8 occur equally often, as do states 5 and 6, and thus can be taken to have the same energy. For the zero-field case the same is true for the two other pairs of states. Each vertex has an associated energy and Boltzmann weight , giving the partition function over the lattice as : where the summation is over all allowed configurations of vertices in the lattice. In this general form the partition function remains unsolved. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Eight-vertex model」の詳細全文を読む スポンサード リンク
|