  We compare the spatial correlations of bond-breaking events and
bond-orientational relaxation in a model two-dimensional liquid undergoing
Newtonian dynamics. We find that the relaxation time of the bond-breaking
correlation function is much longer than the relaxation time of the
bond-orientational correlation function and self-intermediate scattering
function. However, the relaxation time of the bond-orientational correlation
function increases faster with decreasing temperature than the relaxation time
of the bond-breaking correlation function and the self-intermediate scattering
function. Moreover, the dynamic correlation length that characterizes the size
of correlated bond-orientational relaxation grows faster with decreasing
temperature than the dynamic correlation length that characterizes the size of
correlated bond-breaking events. We also examine the ensemble-dependent and
ensemble-independent dynamic susceptibilities for both bond-breaking
correlations and bond-orientational correlations. We find that for both
correlations, the ensemble-dependent and ensemble-independent susceptibilities
exhibit a maximum at nearly the same time, and this maximum occurs at a time
slightly shorter than the peak position of the dynamic correlation length.
