  We present a treatment of the double-slit interference of matter-waves
represented by Gaussian wavepackets. The interference pattern is modelled with
Green's function propagator which emphasizes the coordinate correlations and
phases. We explore the connection between phases and position-momentum
correlations in the intensity, visibility and predictability of the wavepackets
interference. This formulation will indicate some aspects that can be useful
for theoretical and experimental treatment of particles, atoms or molecules
interferometry.
