Sorensen, S. L.Zheng, X.Southworth, S. H.Patanen, M.Kokkonen, E.Oostenrijk, B.Travnikova, O.Marchenko, T.Simon, M.Bostedt, C.Doumy, G.Cheng, L.Young, L.2020-12-232020-12-232020-12-232020-12-2810.1088/1361-6455/abc6bdhttps://infoscience.epfl.ch/handle/20.500.14299/174297WOS:000596725600001A predictive understanding of soft x-ray near-edge absorption spectra of small molecules is an enduring theoretical challenge and of current interest for x-ray probes of molecular dynamics. We report the experimental absorption spectrum for the electron spectroscopy for chemical analysis (ESCA) molecule (ethyl trifluoroacetate) near the carbon 1s absorption edge between 285-300 eV. The ESCA molecule with four chemically distinct carbon sites has previously served as a theoretical benchmark for photoelectron spectra and now for photoabsorption spectra. We report a simple edge-specific approach for systematically expanding standard basis sets to properly describe diffuse Rydberg orbitals and the importance of triple excitations in equation-of-motion coupled-cluster calculations of the energy interval between valence and Rydberg excitations.OpticsPhysics, Atomic, Molecular & ChemicalOpticsPhysicsx-ray spectroscopynexafsxanescoupled-cluster methodsexcited electronic statesabsorption spectroscopyshellcoreexcitationphotoabsorptionatomsprobewatertext::journal::journal article::research article