Non-orthogonal configuration interaction with single substitutions for core-excited states: An extension to doublet radicals
Abstract
In this paper, we present an open-shell extension of the non-orthogonal configuration interaction singles (NOCIS) method for the calculation of core-excited states, intended for peak assignment in XAS spectra of doublet radicals. This extension requires the consideration of additional configurations due to the singly occupied open-shell orbital, and the addition of essential orbital relaxation effects is found to provide a significant improvement on standard CIS, while maintaining the desirable properties of spin purity, variationality, and size consistency. We apply this method to the calculation of core excitations for several open-shell molecules and demonstrate that it performs competitively with other available methods, despite a lack of dynamic correlation. In particular, relative to CVS-ADC(2)-x, RMS error is reduced by a factor of 6 over usual orthogonal CIS and is comparable to time-dependent density functional theory with the best short-range corrected functionals.
Additional Information
© 2019 American Chemical Society. Received: December 18, 2018; Published: April 24, 2019. K.J.O. thanks the members of the Head-Gordon group for fruitful discussions. This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy under contract no. DE-AC02-05CH11231. The authors declare no competing financial interest.Additional details
- Eprint ID
- 94953
- DOI
- 10.1021/acs.jctc.8b01259
- Resolver ID
- CaltechAUTHORS:20190424-160933293
- DE-AC02-05CH11231
- Department of Energy (DOE)
- Created
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2019-04-24Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field