Impurity Energy Level Within The Haldane Gap
نویسندگان
چکیده
An impurity bond J ′ in a periodic 1D 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 ′ < J the level changes gradually from the edge of the Haldane gap to the ground state energy as the deviation dev = (J − J )/J changes from 0 to 1. It seems that there is no threshold. Yet, there is a threshold when J ′ > J . The impurity level appears only when the deviation dev = (J ′ − J)/J ′ is greater than Bc, which is near 0.3 in our calculation. PACS numbers:75.10Jm,76.50+g,75.50.Ee Typeset using REVTEX 1
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