Systematic Inclusion of High-Order Multi-Spin Correlations for the Spin-$\frac{1}{2}$ $XXZ$ Models

R. F. Bishop, R. G. Hale, Y. Xian

We apply the microscopic coupled-cluster method (CCM) to the spin-$\frac{1}{2}$ $XXZ$ models on both the one-dimensional chain and the two-dimensional square lattice. Based on a system…