  Recent progress in measuring the transport properties of individual molecules
has triggered a substantial demand for {\it ab initio} transport calculations.
Even though program packages are commercially available and placed on custom
tailored to address this task, reliable information often is difficult and very
time consuming to attain in the vast majority of cases, namely when the
molecular conductance is much smaller than $e^2/h$. The article recapitulates
procedures for molecular transport calculations from the point of view of
time-dependent density functional theory. Emphasis is describing the
foundations of the ``standard method''. Pitfalls will be uncovered and the
domain of applicability discussed.
