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

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. Here, 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 absencemore » of experimental data.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ; ORCiD logo [1] ;  [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemistry, Chemical Theory Center, Supercomputing Inst.
Publication Date:
Grant/Contract Number:
SC0008666
Type:
Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 8; Journal Issue: 4; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Research Org:
Univ. of Minnesota, Minneapolis, MN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1423814

Ghosh, Soumen, Cramer, Christopher J., Truhlar, Donald G., and Gagliardi, Laura. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems. United States: N. p., Web. doi:10.1039/c6sc05036k.
Ghosh, Soumen, Cramer, Christopher J., Truhlar, Donald G., & Gagliardi, Laura. Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems. United States. doi:10.1039/c6sc05036k.
Ghosh, Soumen, Cramer, Christopher J., Truhlar, Donald G., and Gagliardi, Laura. 2017. "Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems". United States. doi:10.1039/c6sc05036k. https://www.osti.gov/servlets/purl/1423814.
@article{osti_1423814,
title = {Generalized-active-space pair-density functional theory: an efficient method to study large, strongly correlated, conjugated systems},
author = {Ghosh, Soumen and Cramer, Christopher J. and Truhlar, Donald G. and Gagliardi, Laura},
abstractNote = {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. Here, 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.},
doi = {10.1039/c6sc05036k},
journal = {Chemical Science},
number = 4,
volume = 8,
place = {United States},
year = {2017},
month = {1}
}

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