Application of a Two-Step Coupled Cluster Method to the Lipkin-Meshkov-Glick Model

包建華(Chien-Hua Pao)；陳明克(Ming-Keh Chen)；許貞雄(Chen-Shiung Hsue)

Chinese Journal of Physics

25卷3期（1987 / 09 / 01）

425 - 437

英文

We apply the recently proposed two-step coupled cluster method (CCM) to the many-particle pseudospin model of Lipkin, Meshkov and Click. In the first step the variational principle is applied to a coherent state ansatz of the SUB-1 approximation of CCM. Additional correlation energies around the coherent states are added in the second step by a standard method. Excellent results have been obtained for the deformed phase in the Lipkin-Meshkov-Glick model. Comparison with the standard CCM and the extended CCM is also presented. This paper demonstrates that the two-step method also works successfully for the non-abelian system.