Topological quantum phase transition in an S=2 spin chain

We construct a model Hamiltonian for S=2 spin chain, where a variable parameter alpha is introduced. The edge spin is S=1 for alpha=0 and S=3/2 for alpha=1. Due to the topological distinction of the edge states, these two phases must be separated by one or several topological quantum phase transitions. We have studied the quantum phase transition by density matrix renormalization group calculation and proposed a phase diagram for this model.