Weakly bonded complexes of aliphatic and aromatic carbon compounds described with dispersion corrected density functional theory

Interaction energies and structural properties of van der Waals complexes of aliphatic hydrocarbons molecules and crystals of aromatic hydrocarbon compounds are studied using density functional theory augmented with dispersion corrected atom centered potentials (DCACPs). We compare the performance of two sets of DCACPs, (a) DCACP-MP2, a correction for carbon only, generated using MP2 reference data and a penalty functional that includes only equilibrium properties and (b) DCACP-CCSD(T), a set that has been calibrated against CCSD(T) reference data using a more elaborate penalty functional that explicitly takes into account some long-range properties and uses DCACP corrections for hydrogen and carbon atoms. The agreement between our results and high level ab initio or experimental data illustrates the transferability of the DCACP scheme for the gas and condensed phase as well as for different hybridization states of carbon. The typical error of binding energies for gas-phase dimers amounts to 0.3 kcal/mol. This work demonstrates that only one DCACP per element is sufficient to correct for weak interactions in a large variety of systems, irrespective of the hybridization state.