  The accuracy of the noninteracting electron approximation is examined for a
model of vibrationally coupled electron transport in single molecule junction.
In the absence of electronic-vibrational coupling, steady state transport in
this model is described exactly by Landauer theory. Including coupling, both
electronic-vibrational and vibrationally induced electron-electron correlation
effects may contribute to the real time quantum dynamics. Using the multilayer
multiconfiguration time-dependent Hartree (ML-MCTDH) theory to describe nuclear
dynamics exactly while maintaining the noninteracting electron approximation
for the electronic dynamics, the correlation effects are analyzed in different
physical regimes. It is shown that although the noninteracting electron
approximation may be reasonable for describing short time dynamics, it does not
give the correct long time limit for certain initial conditions.
