Electronic charge transfer upon photoexcitation is key to harnessing photon derived energy. Thus, developing and benchmarking a method to directly model electron dynamics is key to understanding these charge transfer processes at a fundamental level. Real-time (RT) TDDFT is a promising, relatively non-standard technique wherein the electron density is directly propagated in time. By propagating the molecular electron density in the time-domain, and combining this density propagation with nuclear motion via the nonadiabatic Ehrenfest method, we can model rates of electron transfer, charge-transfer pathways, frequency-dependent field effects, and nonlinear electron dynamics. Although TDDFT is formally exact, in practice the adiabatic approximation of standard ground state density functionals is used almost exclusively; in this approximation only the instantaneous density is considered and all history dependence of the density is ignored. Additionally, for almost all applications of RT-TDDFT, the time-dependent excited-state density is used as input with standard ground state functionals. However, I will show that some of our recent RT-TDDFT electron dynamics of small model systems treated within this adiabatic approximation yield different time scales of population and dipole oscillation compared to the exact result, while in some cases charge cannot be resonantly transferred between states at all.<br/>

Proceed with caution: Electron dynamics with real-time TDDFT

251st National Meeting (2016)

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