We investigate the S= 1 bilinear-biquadratic model. In some region, the trimerized variational state is a good candidate for the ground state. This explains why the Sutherland model (J1>0 and J2/ J1 = -1) has soft modes at q=0, ±2π/3. Moreover, the full phase diagram of this model is discussed. It is found that at the pure biquadratic ferromagnetic point, the ground state is extremely degenerate.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)