A gapless charge mode induced by the boundary states in the halffilled Hubbard open chain
Abstract
We discuss the ground state and some excited states of the halffilled Hubbard model defined on an open chain with L sites, where only one of the boundary sites has a different value of chemical potential. We consider the case when the boundary site has a negative chemical potential p and the Hubbard coupling U is positive. By an analytic method we show that when p is larger than the transfer integral some of the groundstate solutions of the Bethe ansatz equations become complexvalued. It follows that there is a `surface phase transition' at some critical value 03054470/31/36/006/img5; when 03054470/31/36/006/img6 all the charge excitations have the gap for the halffilled band, while there exists a massless charge mode when 03054470/31/36/006/img7.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 September 1998
 DOI:
 10.1088/03054470/31/36/006
 arXiv:
 arXiv:condmat/9803008
 Bibcode:
 1998JPhA...31.7315D
 Keywords:

 Condensed Matter  Statistical Mechanics
 EPrint:
 Revtex, 25 pages, 3 eps figures