TY - JOUR
T1 - Assessment of conventional density functional schemes for computing the dipole moment and (hyper)polarizabilities of push-pull π-conjugated systems
AU - Champagne, Benoît
AU - Perpète, Eric A.
AU - Jacquemin, Denis
AU - Van Gisbergen, Stan J A
AU - Baerends, Evert Jan
AU - Soubra-Ghaoui, Chirine
AU - Robins, Kathleen A.
AU - Kirtman, Bernard
PY - 2000/5/25
Y1 - 2000/5/25
N2 - DFT schemes based on conventional exchange-correlation (XC) functional have been employed to determine the dipole moment (μ), polarizability (α), and first (β) and second (γ) hyperpolarizabilities of push-pull π-conjugated systems. In addition to the failures already pointed out for α and γ in a recent study on polyacetylene chains [J. Chem. Phys. 1998, 109, 10489; Phys. Rev. Lett. 1999, 83, 694], these functionals are also unsuitable for the evaluation of μ and β. In the case of β, in particular, an almost catastrophic behavior with respect to increasing chain length is found. We show that the C functional has a negligible effect on the calculated μ, α, β, and γ whereas the X-part is responsible for the large property overestimations when the size of the system increases. The overly large μ values are associated with an overestimation of the charge transfer between the donor and the acceptor whereas for α, β, and γ, incomplete screening of the external electric field is responsible for the large discrepancies with respect to accurate values. Our results show that current XC functionals incorrectly describe the polarization of conjugated systems when the polarization is due to donor/acceptor substitution or an external field or both.
AB - DFT schemes based on conventional exchange-correlation (XC) functional have been employed to determine the dipole moment (μ), polarizability (α), and first (β) and second (γ) hyperpolarizabilities of push-pull π-conjugated systems. In addition to the failures already pointed out for α and γ in a recent study on polyacetylene chains [J. Chem. Phys. 1998, 109, 10489; Phys. Rev. Lett. 1999, 83, 694], these functionals are also unsuitable for the evaluation of μ and β. In the case of β, in particular, an almost catastrophic behavior with respect to increasing chain length is found. We show that the C functional has a negligible effect on the calculated μ, α, β, and γ whereas the X-part is responsible for the large property overestimations when the size of the system increases. The overly large μ values are associated with an overestimation of the charge transfer between the donor and the acceptor whereas for α, β, and γ, incomplete screening of the external electric field is responsible for the large discrepancies with respect to accurate values. Our results show that current XC functionals incorrectly describe the polarization of conjugated systems when the polarization is due to donor/acceptor substitution or an external field or both.
UR - http://www.scopus.com/inward/record.url?scp=0343169730&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0343169730
SN - 1089-5639
VL - 104
SP - 4755
EP - 4763
JO - Journal of physical chemistry A
JF - Journal of physical chemistry A
IS - 20
ER -