Introduction and use of generalized Kohn-Sham van der Waals density functionals: Charge relocations in weak interactions

Research Project, 2023 – 2026

I propose to address a challenge for moderndensity functional theory (DFT): understanding charge transferin concert with van der Waals (vdW) forces. To that end I proposeto develop generalized Kohn-Sham (gKS) versions of thevdW density functional (vdW-DF) method that treatscovalent and noncovalent interactions on the samefirst-principles footing. We shall buildon recent experience in defining a pair of fully screenedrange-separated hybrid vdW-DFs.With the vdW-DF-gKS designs, we will gain an elegant way ofnavigating DFT problems where standard exchange-correlation(XC) approximations fail to predict the correct extent ofelectron trapping (for example in oxides) and fail tomaintain a correct XC balance in the presence of complexcharge relocations (for example, occuring in some catalysis andcarbon-capture challenges). The charging strongly impacts thevdW forces that, in turn, help set the electron relocation. Wecan meet that challenge, while also setting the vdW-DF-gKS detailsfrom constraints that apply for the formally exact DFT, becausewe work entirely within an electron-gas foundation.We intend to implement first the vdW-DF-gKS framework andthen to implement the physics constraints on the vdW-DF-gKSdesigns successively. This will be done while validating progressfirst on simple problems, but soon movingto central challenges in catalysis and for selective captureof CO2 in porous structures.