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Cost-effective description of strong correlation [electronic resource] : Efficient implementations of the perfect quadruples and perfect hextuples models

Published
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
Article numbers 134,110 : digital, PDF file
Additional Creators
Lawrence Berkeley National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, United States. Department of Energy. Office of Intelligence and National Security. Office of Intelligence, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Novel implementations based on dense tensor storage are presented here for the singlet-reference perfect quadruples (PQ) [J. A. Parkhill et al., J. Chem. Phys. 130, 084101 (2009)] and perfect hextuples (PH) [J. A. Parkhill and M. Head-Gordon, J. Chem. Phys. 133, 024103 (2010)] models. The methods are obtained as block decompositions of conventional coupled-cluster theory that are exact for four electrons in four orbitals (PQ) and six electrons in six orbitals (PH), but that can also be applied to much larger systems. PQ and PH have storage requirements that scale as the square, and as the cube of the number of active electrons, respectively, and exhibit quartic scaling of the computational effort for large systems. Applications of the new implementations are presented for full-valence calculations on linear polyenes (CnHn+2), which highlight the excellent computational scaling of the present implementations that can routinely handle active spaces of hundreds of electrons. The accuracy of the models is studied in the π space of the polyenes, in hydrogen chains (H50), and in the π space of polyacene molecules. In all cases, the results compare favorably to density matrix renormalization group values. With the novel implementation of PQ, active spaces of 140 electrons in 140 orbitals can be solved in a matter of minutes on a single core workstation, and the relatively low polynomial scaling means that very large systems are also accessible using parallel computing.
Report Numbers
E 1.99:1436139
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Note
Published through SciTech Connect.
10/07/2016.
"ark:/13030/qt3c33d6zr"
Journal of Chemical Physics 145 13 ISSN 0021-9606; JCPSA6 AM
Susi Lehtola; John Parkhill; Martin Head-Gordon.
Funding Information
AC02-05CH11231
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