Relationship between unbranched alkane dimer interaction energies using different theoretical methods and correlations with thermodynamic properties

Abstract 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 E int with respect to those obtained from literature at high levels of theory (MP2 and CCSD(T)). Relationships between E int and experimental heats of vaporization (Δ H v ) and critical temperatures ( T c ) were obtained with MP2, DFT-D, MM and DFTB-LD. This leads to good extrapolations for hairpin-hexadecane using MM3 and DFTB-LD for Δ H v and T c , respectively. Dispersion in DFT is discussed.