Abstract
An impurity bond in a periodic one-dimensional antiferromagnetic spin-1 chain with exchange J is considered. Using the numerical density matrix renormalization-group method, we find an impurity energy level in the Haldane gap, corresponding to a bound state near the impurity bond. When <J the level changes gradually from the edge of the Haldane gap to the ground-state energy as the deviation dev=(J-)/J changes from 0 to 1. It seems that there is no threshold. Yet, there is a threshold when ≳J. The impurity level appears only when the deviation dev=(-J)/ is greater than , which is close to 0.3 in our calculation. © 1996 The American Physical Society.
- Received 19 September 1995
DOI:https://doi.org/10.1103/PhysRevB.53.40
©1996 American Physical Society