A simple fragment-based method for van der Waals corrections over density functional theory

Modelling intermolecular noncovalent interactions between large molecules remains a challenge for electron structure theory community. This is due to the high cost of calculating electron correlation energy. Fragment-based methods usually fare well in reducing the cost of computations in such systems while quantum Drude oscillators turn out to be a good model for van der Waals interactions. In this paper, we have developed a simple yet effective method based on oscillator methods for calculating van der Waals interactions between molecular fragments as a correction to low-cost DFT functional PBE. We have tested our method on S66X8 with significant success.