  In this paper, we study the dynamical behaviors of neutral differential
equations with small delays. We first establish the existence and smoothness of
the global inertial manifolds for these equations. Then we further prove the
smoothness of inertial manifolds with respect to small delays for a certain
class of neutral differential equations. The method can be also applied to deal
with more general small-delay systems. Finally, we apply our main results to
the van der Pol oscillator model with small delay.
