My Research Interests:
My research interests are in quantum field theory and statistical mechanics, especially the lattice spin and fermion models. The main method used in my research is the linked-cluster series expansions. I also interest other methods, like the density matrix renormalisation group (DMRG) method and the spin-wave theory.
My research group have been among the pioneers in developing linked-cluster expansion methods for generating perturbation series in Hamiltonian lattice models. Using this technique, we have generated the longest series available for a variety of spin, fermion and gauge models. For the Heisenberg antiferromagnet, their series results are very accurate, rivalling or exceeding the best Monte Carlo estimates. Recently we have developed a new linked-cluster expansion technique to compute the two-particle bound states and dynamical structure factors, with this we found several new bound states for J1-J2-d chain and some exact results for the 1-particle structure factor of the transverse Ising chain.