Unified many-body approach to van der Waals interactions based on semilocal polarizability functional

Electromagnetic (EM) coupling of charge fluctuations leads to van der Waals (vdW) and Casimir interactions in systems ranging from small molecules to macroscopic bodies. A promising multiscale approach to unified treatment of vdW and Casimir interactions combines microscopic polarizability models of material response with continuous methods for EM field scattering [1]. But existing polarizability models are either limited in scope (atomic models), in efficiency by working with unoccupied one-particle states (e.g., random-phase approximation), or limited to pairwise approximation (nonlocal density functionals). Here, we present a unified method that combines key elements from different theories, and demonstrate its generality on binding in molecular dimers and crystals, carbon-based nanomaterials, oxides, and salts, as well as on adsorption of molecules on metal surfaces. In particular, we develop a semilocal polarizability functional of the electron density and its gradients to parametrize material response and its coupling within the many-body dispersion framework. Our approach allows consistent modelling of a wide range of materials and hybrid materials with mixed bond types.

[1] PS Venkataram, J Hermann, A Tkatchenko, AW Rodriguez, Phys. Rev. Lett. 118, 266802 (2017)