  We study the performance of two different electrode models in quantum
transport calculations based on density functional theory: Parametrized Bethe
lattices and quasi-one dimensional wires or nanowires. A detailed account of
implementation details in both cases is given. From the systematic study of
nanocontacts made of representative metallic elements, we can conclude that
parametrized electrode models represent an excellent compromise between
computational cost and electronic structure definition as long as the aim is to
compare with experiments where the precise atomic structure of the electrodes
is not relevant or defined with precision. The results obtained using
parametrized Bethe lattices are essentially similar to the ones obtained with
quasi one dimensional electrodes for large enough sections of these, adding a
natural smearing to the transmission curves that mimics the true nature of
polycrystalline electrodes. The latter are more demanding from the
computational point of view, but present the advantage of expanding the range
of applicability of transport calculations to situations where the electrodes
have a well-defined atomic structure, as is case for carbon nanotubes, graphene
nanoribbons or semiconducting nanowires. All the analysis is done with the help
of codes developed by the authors which can be found in the quantum transport
toolbox Alacant and are publicly available.
