An efficient implementation of the hierarchical mean-field theory with large block.

We present an efficient implementation of the hierarchical mean-field theory with large block in quantum spin systems. The wave function is a product of the large block states. Each large block state is a superposition of products of small block states. Our result is very close to that of the hierarchical mean-field in a numerical cost effective way. We test our method on a frustrated spin lattice. [ABSTRACT FROM AUTHOR]