The coupled cluster method (CCM) is applied to a spin-half model at zero temperature which interpolates between a triangular lattice antiferromagnet (TAF) and a kagomé lattice antiferromagnet (KAF). The strength of the bonds which connect kagomé lattice sites is J, and the strength of the bonds which link the non-kagomé lattice sites to the kagomé lattice sites on an underlying triangular lattice is $J^{\prime }$. Our results are found to be highly converged, and our best estimate for the ground-state energy per spin for the spin-half KAF ${(J}^{\prime }=0)$ is $-0.4252J.$ The amount of classical ordering on the kagomé lattice sites is also considered, and it is seen that this parameter goes to zero for values of $J^{\prime }$ very close to the KAF point. Further evidence is also presented for CCM critical points which reinforce the conjecture that there is a phase near to the KAF point which is very different to that near to the TAF point ${(J=J}^{\prime }).\mathrm{}$

• Received 9 March 2001

DOI:https://doi.org/10.1103/PhysRevB.63.220402