A Fractionally Ionic Approach to Polarizability and van der Waals Many-Body Dispersion Calculations

Abstract

By explicitly including fractionally ionic contributions to the polarizability of a many-component system, we are able to significantly improve on previous atom-wise many-body van der Waals approaches with essentially no extra numerical cost. For nonionic systems, our method is comparable in accuracy to existing approaches. However, it offers substantial improvements in ionic solids, e.g., producing better polarizabilities by over 65% in some cases. It has particular benefits for two-dimensional transition metal dichalcogenides and interactions of H with modified coronenes, ionic systems of nanotechnological interest. It thus offers an efficient improvement on existing approaches, valid for a wide range of systems.

Evaluation of van der Waals density functionals for layered materials

“…While each group has tradeoffs, an important feature made clear by this figure is that the FIA methods sits at the intersection of the two, and thus achieves a balance between energies and lattice constants. Note that standard MBD theory fails completely for transition metal dichalcogenides [14] and has been left out of these tests.…”

Benchmarking several van der Waals dispersion approaches for the description of intermolecular interactions

“…In this section, we summarize the general theoretical background of the methods used in this work, from non-local van der Waals density functionals to the differents schemes proposed by Tkatchenko and Scheffler 6 (TS) and their variants, which include self-consistent screening 32 (SCS) or many-body dispersion (MBD) interactions [32][33][34] . Summaries on some of the theoretical advantages and disadvantages of these approaches can also be found in Refs.…”

“…Further refinements were proposed by Gould et al 34 that led to improvements in more difficult nanosystems. Firstly, by using the gas phase polarizabilities of fractional ions 52 , the ionic nature of the system is fully taken into account.…”

Benchmarking Several van der Waals Dispersion Approaches for the Description of Intermolecular Interactions

“…In this section, we summarize the general theoretical background of the methods used in this work, from non-local van der Waals density functionals to the differents schemes proposed by Tkatchenko and Scheffler 6 (TS) and their variants, which include self-consistent screening 32 (SCS) or many-body dispersion (MBD) interactions [32][33][34] . Summaries on some of the theoretical advantages and disadvantages of these approaches can also be found in…”