Benchmarking TD-DFT and Wave Function Methods for Oscillator Strengths and Excited-State Dipole Moments

Using a set of oscillator strengths and excited-state dipole moments near full configuration interaction (FCI) quality determined for small compounds, we benchmark the performances several single-reference wave function methods (CC2, CCSD, CC3, CCSDT, ADC(2), ADC(3/2)) time-dependent density-functional theory (TD-DFT) with various functionals (B3LYP, PBE0, M06-2X, CAM-B3LYP, $\omega$B97X-D). We consider impact gauges (length, velocity, mixed) formalisms: equation motion (EOM) \emph{vs} linear response (LR), relaxed unrelaxed orbitals, etc. Beyond expected accuracy improvements neat decrease formalism sensitivy when using higher-order methods, present contribution shows that, both ADC(2) CC2, choice gauge impacts more significantly magnitude than formalism, that CCSD yields notable improvement on this transition property as compared to CC2. For moments, switching orbital relaxation appreciably improves but has rather effect at level. Going from ground excited states, typical errors given method tend roughly triple. Interestingly, ADC(3/2) dipoles are accurate their counterparts, whereas two models do deliver similar absolute energies. Concerning TD-DFT, one finds: i) negligible all tested (except M06-2X); ii) deviations ca.~0.10 D ground-state functionals; iii) better overall performance CAM-B3LYP considered properties.