CH/pi interaction in benzene and substituted derivatives with halomethane: a combined density functional and dispersion-corrected density functional study.

The present work intends to establish the efficiency of dispersion-corrected density functionals in explaining the potential energy curves of benzene-methane, benzene-fluoroform, and 1,3,5-trifluoro benzene-methane complexes. The interaction energies of all of the complexes under investigation have been evaluated using both van der Waals-corrected and normal gradient-corrected Perdew-Burke-Ernzerhof and Becke-Lee-Yang-Parr density functionals. Our analyses suggest that the potential energy curves for both benzene-methane and benzene-fluoroform complexes are in excellent agreement with highly accurate coupled cluster (CCSD(T)) results as well as high-level counterpoise-corrected MP2 results. Remarkably, the interaction energies of the benzene-fluoroform complex are fairly higher than those of the other two complexes. This is primarily attributed to the dispersion correction present in it. Finally, the overall study highlights the importance of halogen substitution in strengthening the CH/pi interactions.