Electron density distribution in stacked benzene dimers: a new approach towards the estimation of stacking interaction energies.

The potential energy surface for the benzene dimer in stacked conformations (84 points calculated) was computed at the MP2(FC)6-31+G(2d,2p) level of theory. Electron density (ED) distribution computed using the MP2(FC), B3LYP, and Hartree-Fock methods with the same basis set is studied in the frame of topological analysis. It is found that ED topology does not depend on the method of calculation. The values of the ED and its Laplacian in the cage critical point calculated using different methods are determined to be linearly dependent with the slope depending on basis set. Correlation equations based on these properties allow the interaction energy between benzene rings to be predicted with 8% mean relative error in the energy for the given region of the potential energy surface. This provides a new method for the estimation of stacking interaction energy using ED properties calculated with low level quantum-chemical methods.