Spin-Liquid State for Two-Dimensional Heisenberg Antiferromagnets on a   Triangular Lattice
  The spin liquid state of the antiferromagnetic Heisenberg model on a triangular lattice is studied within the self-consistent Green's function method. It is shown that the spin excitation spectra is gapless, and ground-state energy per site is $E_{g}/NJ=-0.966$, which is in very good agreement with the results obtained within the variational Monte Carlo method based on the resonating-valence-bond state. Some thermodynamic properties are also discussed. 
Zhan-hai Dong and Shiping Feng