Abstract
Lattice constant and cohesive energy are basic properties in the design of materials and devices. However, due to neglect of long-range van der Waals (vdW) interactions, density functional approximations (DFAs) often yield unusually large errors for ionic solids and heavy metals. Here, we propose a model for the dynamically screened vdW correction, including the leading order as well as higher-order contributions. The striking feature of this model is that important screening effects and higher-order contributions are properly considered and that its contribution to the short-range part is removed by a novel damping function for the avoidance of double counting. As a result, the model dramatically reduces the error of the DFA-GGA in lattice constant and cohesive energy. We also find that the three-body interactions are small, due to the screening effects. These observations greatly improve our fundamental understanding of vdW interactions and enhance the applicability of efficient semilocal DFAs.
- Received 6 April 2017
DOI:https://doi.org/10.1103/PhysRevMaterials.1.020802
©2017 American Physical Society