  We investigate large scale structure formation of collisionless dark matter
in the phase space description based on the Vlasov-Poisson equation. We present
the Schr\"odinger method, originally proposed by Widrow and Kaiser (1993) as
numerical technique based on the Schr\"odinger Poisson equation, as an
analytical tool which is superior to the common standard pressureless fluid
model. Whereas the dust model fails and develops singularities at shell
crossing the Schr\"odinger method encompasses multi-streaming and even
virialization.
