Charge-Transfer Steps in Density Functional Theory from the Perspective of the Exact Electron Factorization

When a molecule dissociates, the exact Kohn–Sham (KS) and Pauli potentials may form step structures. Reproducing these steps correctly is central for description of dissociation charge-transfer processes in density functional theory (DFT): The align KS eigenvalues dissociating subsystems relative to each other determine where electrons localize. While height can be calculated from asymptotic behavior orbitals, this provides limited insight into what causes steps. We give an explanation with mapping many-electron problem one-electron problem, electron factorization (EEF). appearing EEF have clear physical meaning that translates DFT by replacing interacting system system. With simple model diatomic, we illustrate are consequence spatial entanglement result charge transfer. From mechanism, immediately deduced. Moreover, two methods approximately reproduce during proposed. One based on states dissociated system, while one analogy Born–Oppenheimer treatment molecule. latter method also shows connect adiabatic potential energy surfaces. view thus better understanding how effects encoded they modeled.