Direct calculation of the spin stiffness of the spin- 1 2 Heisenberg antiferromagnet on square, triangular, and cubic lattices using the coupled-cluster method

We present a method for the direct calculation of the spin stiffness by means of the coupled-cluster method. For the spin- 1 2 Heisenberg antiferromagnet on square, triangular, and cubic lattices, we calculate the stiffness in high orders of approximation. For square and cubic lattices, our results are in very good agreement with the best results available in the literature. For the triangular lattice, our result is more precise than any other result obtained thus far by other approximate method. © 2006 The American Physical Society.