Assessment of a Nonlocal Correction Scheme to Semilocal Density Functional Theory Methods.

A nonlocal correction method to (semi)local density-functional theory (DFT) methods is derived that is based on a partitioning of the correlation-energy density into atom-atom contributions. Nonlocal interaction contributions, which are absent in standard DFT methods, are introduced in this method by using atomic weight functions that do not vanish exponentially as the atomic densities but with the inverse sixth power of the atomic distances. The parameters contained in these weight functions were fitted to reproduce intermolecular interaction energies for a range a small dimer systems. The new functional has then been tested both for intermolecular interactions, using the S22, S66 × 8, and IonHB databases from Hobza et al., and for other thermodynamical properties using a subset of 14 databases of the GMTKN30 database of Grimme et al. It is found that for intermolecular interactions the accuracy of the method is often higher than with standard DFT+D methods while for other properties, such as reaction energies or relative conformation energies of medium sized organic molecules, the accuracy is similar to hybrid-DFT+D methods. The nonlocal correction method has been tested also to predict the interaction energy of the water-graphene system yielding an estimated interaction energy of -2.87 kcal/mol, which is in line with previous theoretical investigations.