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Structural effects on the low cubic hyperpolarizability of C 60 : A scaling of conjugation in three‐dimensional curvature of π‐conjugation systems
Author(s) -
Lin YingTing,
Lee ShyiLong
Publication year - 1999
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1999)75:4/5<457::aid-qua12>3.0.co;2-x
Subject(s) - hyperpolarizability , planarity testing , scaling , chemistry , curvature , computational chemistry , chemical physics , molecular physics , crystallography , organic chemistry , polarizability , molecule , mathematics , geometry
The semiempirical AM1‐calculated cubic hyperpolarizability is found to be surprisingly low in C 60 , which is in agreement with recent experimental results. (In the past, 10 orders of magnitude discrepancy has existed in the literature for the cubic hyperpolarizabilities of C 60 ). Comparing some selected groups of polyaromatic hydrocarbons, we show that linearity and planarity are two dominating factors in the second hyperpolarizability in polyaromatic rings. Therefore, the observations that aromatic rings on C 60 lose their linearity and planarity account for the low second hyperpolarizability. Furthermore, the planarity defined mathematically can be served as a scale of conjugation in π‐conjugation systems. By using biphenyl as a reference, the cubic hyperpolarizability of C 60 can be estimated by the scaling of conjugation. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 457–463, 1999