  The quasiparticle resonant states around a single nonmagnetic impurity with
unitary scattering in a d-wave superconductor is studied by solving the
Bogoliubov-de Gennes equations based on a t-J model. Both the spatial variation
of the order parameter and the local density of states (LDOS) around the
impurity have been investigated. We find: (i) A particle-hole symmetric system
has a single symmetric zero-energy peak in the LDOS regardless of the size of
the superconducting coherence length \xi_0; (ii) For the particle-hole
asymmetric case, an asymmetric splitting of the zero-energy peak is intrinsic
to a system with a small value of k_{F}\xi_0.
