Approximate spin projected spin-unrestricted density functional theory method: Application to diradical character dependences of second hyperpolarizabilities

Journal Article · Thu Jan 22 04:00:00 EST 2015 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4906627· OSTI ID:22390901

Nakano, Masayoshi; Minami, Takuya; Fukui, Hitoshi; Yoneda, Kyohei; Shigeta, Yasuteru; Kishi, Ryohei ^[1]; Champagne, Benoît; Botek, Edith ^[2]

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1. Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan)
2. Laboratoire de Chimie Théorique, Facultés Universitaires Notre-Dame de la Paix (FUNDP), rue de Bruxelles, 61, 5000 Namur (Belgium)

We develop a novel method for the calculation and the analysis of the one-electron reduced densities in open-shell molecular systems using the natural orbitals and approximate spin projected occupation numbers obtained from broken symmetry (BS), i.e., spin-unrestricted (U), density functional theory (DFT) calculations. The performance of this approximate spin projection (ASP) scheme is examined for the diradical character dependence of the second hyperpolarizability (γ) using several exchange-correlation functionals, i.e., hybrid and long-range corrected UDFT schemes. It is found that the ASP-LC-UBLYP method with a range separating parameter μ = 0.47 reproduces semi-quantitatively the strongly-correlated [UCCSD(T)] result for p-quinodimethane, i.e., the γ variation as a function of the diradical character.

• OSTI ID: 22390901
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1642; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
DENSITY FUNCTIONAL METHOD
ELECTRONS
PERFORMANCE
POLARIZABILITY
SPIN
SYMMETRY BREAKING
VARIATIONS