Issue 4, 2017

Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

Abstract

Predicting ground- and excited-state properties of open-shell organic molecules by electronic structure theory can be challenging because an accurate treatment has to correctly describe both static and dynamic electron correlation. Strongly correlated systems, i.e., systems with near-degeneracy correlation effects, are particularly troublesome. Multiconfigurational wave function methods based on an active space are adequate in principle, but it is impractical to capture most of the dynamic correlation in these methods for systems characterized by many active electrons. We recently developed a new method called multiconfiguration pair-density functional theory (MC-PDFT), that combines the advantages of wave function theory and density functional theory to provide a more practical treatment of strongly correlated systems. Here we present calculations of the singlet–triplet gaps in oligoacenes ranging from naphthalene to dodecacene. Calculations were performed for unprecedently large orbitally optimized active spaces of 50 electrons in 50 orbitals, and we test a range of active spaces and active space partitions, including four kinds of frontier orbital partitions. We show that MC-PDFT can predict the singlet–triplet splittings for oligoacenes consistent with the best available and much more expensive methods, and indeed MC-PDFT may constitute the benchmark against which those other models should be compared, given the absence of experimental data.

Graphical abstract: Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

Supplementary files

Article information

Article type
Edge Article
Submitted
14 Nov. 2016
Accepted
16 Janv. 2017
First published
19 Janv. 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2017,8, 2741-2750

Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems

S. Ghosh, C. J. Cramer, D. G. Truhlar and L. Gagliardi, Chem. Sci., 2017, 8, 2741 DOI: 10.1039/C6SC05036K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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