Nonresonant frequency dispersion of the electronic second hyperpolarizability of all-trans polysilane chains: An ab initio TDHF oligomeric approach
✍ Scribed by Benoît Champagne; Éric A. Perpète; Jean-Marie André
- Book ID
- 101253089
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 345 KB
- Volume
- 70
- Category
- Article
- ISSN
- 0020-7608
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✦ Synopsis
The frequency-dependent electronic second hyperpolarizability of increasingly large polysilane chains is computed for the most common nonlinear optical Ž . NLO processes at the time-dependent Hartree᎐Fock level with the 6-31G atomic basis Ž e . set. Due to -conjugation, the longitudinal component ␥ turns out to be dominant. Its L nonresonant dispersion relations are described by the coefficients of the power expansion e Ž . e Ž . w 2 4 6
x 2 formula, ␥ y ; , , s ␥ 0; 0, 0, 0 1 q A q B q C q иии , where s
e Ž . q q q and ␥ 0; 0, 0, 0 is the static limit value. In the infinite chain length 1 2 3 L limit, the CHFr6-31G static longitudinal electronic second hyperpolarizability per Si H 2 4
unit cell is estimated to attain 463 " 10 = 10 3 a.u. whereas the A coefficient reaches 27.8 " 0.9 a.u. The accuracy that could be reached from using this power expansion expression for estimating the second hyperpolarizability for other optical frequencies is discussed.