  We study the long time dynamics of the defocussing NLS equation. Compared
with previous literature, we revisit the direct and inverse scattering map to
obtain asymptotics in some weighted energy space that requires less restrictive
decay and regularity assumptions. The main result is derived from an
application of uniform resolvent bound and an approximation argument in the
spirit of Riemann-Lebesgue lemma. As a consequence, our result depicts the long
time dynamics of the zeros of the solution to the defocussing NLS equation.
