Simple, Exact Asymptotic Density Functional Theory

An exact, computationally efficient density functional theory (DFT) ansatz is derived using the asymptotic limits of large and small interatomic separations. A generalization of the Anderson-Weeks-Adams-Gilbert chemical pseudopotential theory of localized atomic states, asymptotic density functional theory (ADFT) recasts the Kohn-Sham equations in a simple, self-consistent Huckel form that features nonempirical Hamiltonian matrix elements and explicit exchange-correlation (XC), electrostatic, and orthogonalization effects. The theory provides fundamental justification for several characteristics of successful tight binding models, most notably the atomic additivity of electron density and the potential and the pairwise additivity of interatomic XC, electrostatic, and Pauli repulsion effects. The Sanderson electronegativity equalization principle and the charge equilibration mechanism resembling the Rappe-Goddard scheme naturally follow. ADFT offers a bridge between molecular orbital, valence bond, and DFT theories and holds promise to accelerate accurate quantum chemical calculations.
24 pages, 103 equations