Time-dependent density functional theory (TDDFT) in the linear-response regime is the workhorse for the calculation of electronic excited states in large systems. However, core-excited states are problematic in TDDFT due to an improper description of particle-hole interactions and a lack of orbital relaxation. Particle-hole interaction refers to the excited electron interact- † Electronic Supplementary Information (ESI) available: Linear shifts applied to all spectra, histogram spectra, and comparison between full EA-TDDFT and EA-TDDFT within the Tamm-Dancoff approximation. See DOI: 00.0000/00000000. ‡ E-mail: carter-fenk@berkeley.edu § E-mail: mhg@cchem.berkeley.edu ing with the Coulomb hole left behind in the donor orbital after vertical excitation. This effect is totally absent in pure density functionals and only partially captured by hybrid functionals due to the inexact treatment of exchange in density functional theory (DFT). In the context of XAS, orbital relaxation refers to the strong polarizing effect on all orbitals due to removing an electron from a core orbital and is deficient in all varieties of linear-response methods that include only singly-excited configurations in a wave function generated from ground-state reference orbitals. While TDDFT has shown some promise in modeling liquid-phase XAS, very few studies exist on the topic, and therefore the importance of orbital relaxation and particle-hole interaction errors in the condensed phase are yet to be thoroughly assessed.