School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK.
J Phys Condens Matter. 2011 Oct 12;23(40):406001. doi: 10.1088/0953-8984/23/40/406001. Epub 2011 Sep 21.
The coupled-cluster method is applied to the spin-1/2 antiferromagnetic XXZ model on a square lattice by employing an approximation which contains two-body long-range correlations and high-order four-body local correlations. Improvement is found for the ground-state energy, the sublattice magnetization and the critical anisotropy when comparing with the approximation including the two-body correlations alone. We also obtain the full excitation spectrum which is in good agreement with the quantum Monte Carlo results and the high-order spin-wave theory.
该文采用包含双体长程关联和高阶四体局域关联的近似方法，将耦合簇方法应用于在正方形晶格上的自旋为 1/2 的反铁磁 XXZ 模型。通过与仅包含双体关联的近似方法进行比较，我们发现该近似方法能够提高基态能量、子晶格磁化强度和临界各向异性。我们还得到了完整的激发能谱，与量子蒙特卡罗结果和高阶自旋波理论吻合得很好。
