Dynamics of Charge-Transfer Processes with Time-Dependent Density Functional Theory

We show that as an electron transfers between closed-shell molecular fragments at large separation, the exact correlation potential of time-dependent density functional theory gradually develops a step and peak structure in the bonding region. This structure has a density-dependence that is non-local both in space and time, and even the exact ground-state exchange-correlation functional fails to cap- ture it. In the complementary case of charge-transfer between open-shell fragments, an initial step and peak vanish as the charge-transfer state is reached. Lack of these structures in usual approxima- tions leads to inaccurate charge-transfer dynamics. This is dramatically illustrated by the complete lack of Rabi oscillations in the dipole moment under conditions of resonant charge-transfer

Dynamics of charge-transfer processes with time-dependent density functional theory

arXiv:1211.2849We show that whenever an electron transfers between closed-shell molecular fragments, the exact correlation potential of time-dependent density functional theory develops a step and peak structure in the bonding region. This structure has a density dependence that is nonlocal both in space and in time that even the exact adiabatic ground-state exchange–correlation functional fails to capture it. For charge-transfer between open-shell fragments, an initial step and peak vanish as the charge-transfer state is reached. The inability of usual approximations to develop these structures leads to inaccurate charge-transfer dynamics. This is illustrated by the complete lack of Rabi oscillations in the dipole moment under conditions of resonant charge transfer for an exactly solvable model system. The results transcend the model and are applicable to more realistic molecular complexes.We gratefully acknowledge financial support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Award DE-SC0008623 (N.T.M.) and a grant of computer time from the CUNY High Performance Computing Center under NSF Grant CNS-0855217. The European Research Council (ERC-2010-AdG-267374), Spanish: FIS2011-65702-C02-01), Grupos Consolidados (IT-319-07), and EC Projects CRONOS (280879-2) and CNS-0958379 are gratefully acknowledged. J.I.F. acknowledges support from an FPI fellowship (FIS2007-65702-C02-01).Peer Reviewe