Discrete-lattice model for surface bound states and tunneling in d-wave superconductors

Surface bound states in a discrete-lattice model of a d(x)(2)-(2)(y) cuprate superconductor are shown to be, in general, coherent superpositions of an incoming excitation and more than one outgoing excitation, and a simple graphical construction based on a surface-adapted Brillouin zone is developed to describe their nature. In addition, a momentum-dependent lifetime contribution to the width of these bound states as observed in tunneling experiments is derived and elucidated in physical terms. [S0163-1829(99)10801-4].