TY - JOUR
T1 - Long-range corrected density functional theory study on static second hyperpolarizabilities of singlet diradical systems
AU - Kishi, Ryohei
AU - Bonness, Sean
AU - Yoneda, Kyohei
AU - Takahashi, Hideaki
AU - Nakano, Masayoshi
AU - Botek, Edith
AU - Champagne, Benoit
AU - Kubo, Takashi
AU - Kamada, Kenji
AU - Ohta, Koji
AU - Tsuneda, Takao
PY - 2010/3/19
Y1 - 2010/3/19
N2 - Within the spin-unrestricted density functional theory (DFT) the long-range correction (LC) scheme combined with the Becke-Lee-Yang-Parr exchange-correlation functional, referred to as LC-UBLYP method, has been applied to the calculation of the second hyperpolarizability (γ) of open-shell singlet diradical systems of increasing complexity and has demonstrated good performance: (i) for the simplest H2 dissociation model, the γ values calculated by the LC-UBLYP method significantly overshoot the full configuration interaction result but reproduce qualitatively the evolution of γ as a function of the diradical character, (ii) for small singlet diradical 1,3-dipole systems, the diradical character dependence of γ determined by the UCCSD and UCCSD(T) reference methods is reproduced semiquantitatively by the LC-UBLYP method except in the small diradical character region, where the spin-unrestricted solutions coincide with spin-restricted solutions, (iii) the LC-UBLYP method also closely reproduces the UCCSD(T) results on the diradical character dependence of γ of the p -quinodimethane model system, particularly in the intermediate and large diradical character regions, whereas it shows an abrupt change for a diradical character (y) close to 0.2 originating from the triplet instability, (iv) the reliability of LC-UBLYP to reproduce reference coupled cluster results on open-shell singlet systems with intermediate and large diradical characters has also been substantiated in the case of γ of 1,4-bis-(imidazol-2-ylidene)- cyclohexa-2,5-diene (BI2Y), then (v), for real systems built from a pair of phenalenyl radicals separated by a conjugated linker, the LC-UBLYP results have been found to closely match the UBHandHLYP values-which, for small systems are in good agreement with those obtained using correlated molecular orbital methods-whereas the UB3LYP results can be much different. These results are not only important from the viewpoint of an efficient determination of the nonlinear optical properties of open-shell singlet systems, but also from the viewpoint of defining new challenges for elaborating improved exchange-correlation functionals.
AB - Within the spin-unrestricted density functional theory (DFT) the long-range correction (LC) scheme combined with the Becke-Lee-Yang-Parr exchange-correlation functional, referred to as LC-UBLYP method, has been applied to the calculation of the second hyperpolarizability (γ) of open-shell singlet diradical systems of increasing complexity and has demonstrated good performance: (i) for the simplest H2 dissociation model, the γ values calculated by the LC-UBLYP method significantly overshoot the full configuration interaction result but reproduce qualitatively the evolution of γ as a function of the diradical character, (ii) for small singlet diradical 1,3-dipole systems, the diradical character dependence of γ determined by the UCCSD and UCCSD(T) reference methods is reproduced semiquantitatively by the LC-UBLYP method except in the small diradical character region, where the spin-unrestricted solutions coincide with spin-restricted solutions, (iii) the LC-UBLYP method also closely reproduces the UCCSD(T) results on the diradical character dependence of γ of the p -quinodimethane model system, particularly in the intermediate and large diradical character regions, whereas it shows an abrupt change for a diradical character (y) close to 0.2 originating from the triplet instability, (iv) the reliability of LC-UBLYP to reproduce reference coupled cluster results on open-shell singlet systems with intermediate and large diradical characters has also been substantiated in the case of γ of 1,4-bis-(imidazol-2-ylidene)- cyclohexa-2,5-diene (BI2Y), then (v), for real systems built from a pair of phenalenyl radicals separated by a conjugated linker, the LC-UBLYP results have been found to closely match the UBHandHLYP values-which, for small systems are in good agreement with those obtained using correlated molecular orbital methods-whereas the UB3LYP results can be much different. These results are not only important from the viewpoint of an efficient determination of the nonlinear optical properties of open-shell singlet systems, but also from the viewpoint of defining new challenges for elaborating improved exchange-correlation functionals.
UR - http://www.scopus.com/inward/record.url?scp=77949373692&partnerID=8YFLogxK
U2 - 10.1063/1.3332707
DO - 10.1063/1.3332707
M3 - Article
AN - SCOPUS:77949373692
SN - 0021-9606
VL - 132
JO - The Journal of chemical physics
JF - The Journal of chemical physics
IS - 9
M1 - 094107
ER -