Interaction energies (E-int) were evaluated for n-alkanes dimers (C1-C10) using DFT-D, different functionals, and several basis sets. In addition, calculations were also carried out with DFTB-LD and MM3 and OPLS-AA force fields. Results show linear correlations of Eint with respect to those obtained from literature at high levels of theory (MP2 and CCSD(T)). Relationships between Eint and experimental heats of vaporization (Delta H-v) and critical temperatures (T-c) were obtained with MP2, DFT-D, MM and DFTBLD. This leads to good extrapolations for hairpin-hexadecane using MM3 and DFTB-LD for Delta H-v, and T-c, respectively. Dispersion in DFT is discussed. (C) 2015 Elsevier B.V. All rights reserved.