Trimerized ground state of the spin-1 Heisenberg antiferromagnet on the   kagome lattice
  We study the phase diagram of the spin-1 quantum bilinear-biquadratic antiferromagnet on the kagome lattice using exact diagonalization and the density matrix renormalization group algorithm. The SU(3)-symmetric point of this model Hamiltonian is a spontaneously trimerized state whose qualitative nature persists even at the Heisenberg point, a finding that contrasts previous proposals. We report the ground state energy per site of the Heisenberg model to be -1.410(2) and establish the presence of a spin gap. 
Hitesh J. Changlani, Andreas M. L\"auchli
cond-mat.str-el