  We present a new method to reconstruct the primordial (linear) density field
using the estimated nonlinear displacement field. The divergence of the
displacement field gives the reconstructed density field. We solve the
nonlinear displacement field in the 1D cosmology and show the reconstruction
results. The new reconstruction algorithm recovers a lot of linear modes and
reduces the nonlinear damping scale significantly. The successful 1D
reconstruction results imply the new algorithm should also be a promising
technique in the 3D case.
