Adaptive Configuration Interaction for Computing Challenging Electronic Excited States with Tunable Accuracy

• Published in: Journal of chemical theory and computation Vol. 13; no. 11; pp. 5354 - 5366
• Main Authors: Schriber, Jeffrey B, Evangelista, Francesco A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.11.2017
• Subjects: Charge transfer; Computation; Configuration interaction; Electron states; Lithium fluoride
• ISSN: 1549-9618; 1549-9626
• DOI: 10.1021/acs.jctc.7b00725

We introduce and analyze various approaches for computing excited electronic states using our recently developed adaptive configuration interaction (ACI) method [ Schriber, J. B. ; Evangelista, F. A. J. Chem. Phys. 2016, 144, 161106 ]. These ACI methods aim to describe multiple electronic states with equal accuracy, including challenging cases like multielectron, charge-transfer, and near-degenerate states. We develop both state-averaged and state-specific approaches to compute excited states whose absolute energy error can be tuned by a user-specified energy error threshold, σ. State-averaged schemes are found to be more efficient in that they obtain all of the states simultaneously in one computation, but they lose some degree of statewise tunability. State-specific algorithms allow for direct control of the error of each state, though the states must be computed sequentially. We compare each method using methylene, LiF, and all-trans polyene benchmark data.