  We evaluate various analytical models for the electron-ion energy transfer
and compare the results to data from molecular dynamics (MD) simulations. The
models tested includes energy transfer via strong binary collisions,
Landau-Spitzer rates with different choices for the cut-off parameters in the
Coulomb logarithm, rates based on Fermi's golden rule (FGR) and theories taking
coupled collective modes (CM) into account. In search of a model easy to apply,
we first analyze different approximations of the FGR energy transfer rate. Then
we investigate several numerical studies using MD simulations and try to
uncover CM effects in the data obtained. Most MD data published so far show no
distinct CM effects and, thus, can be interpreted within a FGR or binary
collision approach. We show that this finding is related to the parameter
regime, in particular the initial temperature difference, considered in these
investigations.
