Nonlocal Van Der Waals Density Functionals Based on Local Response Models

Abstract

As described in Chapter 22, dispersion interactions, also known as van der Waals interactions, arise from long-range correlated fluctuations of the electron charge density. The dispersion energy is thus a nonlocal component of the correlation energy. In practical applications of Kohn--Sham DFT, the correlation energy is usually approximated as a local or a semilocal density functional. (Semi)local functionals cannot in principle include the proper physics of long-range dispersion interactions. Empirical dispersion corrections are quite popular and reasonably successful , but they typically entail a departure from pure DFT into the realm of classical force fields, and hence they fall outside the scope of this book. The rigorous description of long-range van der Waals interactions requires fully nonlocal treatment of correlation.