  The ground state of a one-dimensional spin-1/2 chain with periodical boundary
condition in the Heisenberg XY model is investigated. We consider the spatial
correlation and concurrence between any nearest-neighbor pair of spins under
the conditions of different coupling strength, anisotropic parameter and
magnitude of a transverse field. Quantum phase transitions due to the
competition between coupling and alignment which cause the abrupt changes of
the correlation and concurrence are observed. The transition are direct results
of the level crossing.
