  We present density functional theory calculations of the geometry, adsorption
energy and electronic structure of thiophene adsorbed on Cu(111), Cu(110) and
Cu(100) surfaces. Our calculations employ dispersion corrections and
self-consistent van der Waals density functionals (vdW-DFs). In terms of speed
and accuracy, we find that the dispersion-energy-corrected Revised
Perdue-Burke-Enzerhof (RPBE) functional is the "best balanced" method for
predicting structural and energetic properties, while vdW-DF is also highly
accurate if a proper exchange functional is used. Discrepancies between theory
and experiment in molecular geometry can be solved by considering x-ray
generated core-holes. However, the discrepancy concerning the adsorption site
for thiophene/Cu(100) remains unresolved and requires both further experiments
and deeper theoretical analysis. For all the interfaces, the PBE functional
reveals a covalent bonding picture which the inclusion of dispersive
contributions does not change to a vdW one. Our results provide a comprehensive
understanding of the role of dispersive forces in modelling molecule-metal
interfaces.
