Cost and sensitivity of restricted active-space calculations of metal L-edge X-ray absorption spectra
Number of Authors: 5
2016 (English)In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 37, no 5, 477-486 p.Article in journal (Refereed) Published
The restricted active-space (RAS) approach can accurately simulate metal L-edge X-ray absorption spectra of first-row transition metal complexes without the use of any fitting parameters. These characteristics provide a unique capability to identify unknown chemical species and to analyze their electronic structure. To find the best balance between cost and accuracy, the sensitivity of the simulated spectra with respect to the method variables has been tested for two models, [FeCl6](3-) and [Fe(CN)(6)](3-). For these systems, the reference calculations give deviations, when compared with experiment, of 1 eV in peak positions, 30% for the relative intensity of major peaks, and 50% for minor peaks. When compared with these deviations, the simulated spectra are sensitive to the number of final states, the inclusion of dynamical correlation, and the ionization potential electron affinity shift, in addition to the selection of the active space. The spectra are less sensitive to the quality of the basis set and even a double- basis gives reasonable results. The inclusion of dynamical correlation through second-order perturbation theory can be done efficiently using the state-specific formalism without correlating the core orbitals. Although these observations are not directly transferable to other systems, they can, together with a cost analysis, aid in the design of RAS models and help to extend the use of this powerful approach to a wider range of transition metal systems.
Place, publisher, year, edition, pages
2016. Vol. 37, no 5, 477-486 p.
transition metals, X-ray absorption spectroscopy, multiconfigurational wavefunction, spin-orbit coupling, charge transfer
IdentifiersURN: urn:nbn:se:su:diva-127345DOI: 10.1002/jcc.24237ISI: 000369176900002PubMedID: 26502979OAI: oai:DiVA.org:su-127345DiVA: diva2:911310