Studies of Spuriously Time-dependent Resonances in Time-dependent Density Functionl Theory

KAI LUO; JOHANNA I FUKS; NEEPA T. MAITRA

JOURNAL OF CHEMICAL PHYSICS

AMER INST PHYSICS

Lugar: New York; Año: 2016 vol. 145

0021-9606

Adiabatic approximations in time-dependent density functional theory (TDDFT) will in generalyield unphysical time-dependent shifts in the resonance positions of a system driven far from itsground-state. This spurious time-dependence is explained in Fuks et al. [Phys. Rev. Lett. 114, 183002(2015)] in terms of the violation of an exact condition by the non-equilibrium exchange-correlationkernel of TDDFT. Here we give details on the derivation and discuss reformulations of the exactcondition that apply in special cases. In its most general form, the condition states that when a systemis left in an arbitrary state, the TDDFT resonance position for a given transition in the absence oftime-dependent external fields and ionic motion is independent of the state. Special cases includethe invariance of TDDFT resonances computed with respect to any reference interacting stationarystate of a fixed potential, and with respect to any choice of appropriate stationary Kohn-Shamreference state. We then present several case studies, including one that utilizes the adiabaticallyexact approximation, that illustrate the conditions and the impact of their violation on the accuracyof the ensuing dynamics. In particular, charge-transfer across a long-range molecule is hampered,and we show how adjusting the frequency of a driving field to match the time-dependent shift in thecharge-transfer resonance frequency results in a larger charge transfer over time.