Saturation of the second hyperpolarizability for polyacetylenes

Autor:	Murco N. Ringnalda, Daqi Lu, William A. Goddard, Richard A. Friesner, Bryan Marten
Rok vydání:	1996
Předmět:	chemistry.chemical_classification Polyacetylene chemistry.chemical_compound chemistry Computational chemistry Ab initio quantum chemistry methods General Physics and Astronomy Physical chemistry Hyperpolarizability Polymer Physical and Theoretical Chemistry Saturation (magnetic)
Zdroj:	Chemical Physics Letters. 257:224-228
ISSN:	0009-2614
DOI:	10.1016/0009-2614(96)00458-7
Popis:	Polyacetylene (PA) polymers −(−CHCH−)N− lead to large second hyperpolarizabilities (γ) that increase with N. For small N the increase is quite rapid, eventually saturating (becoming linear in N) for N ⩾ Nsatγ. Both experimental and theoretical attempts have been made to estimate Nsatγ. In 1994 this led to two Science papers, one obtaining Nsatγ = 20 (semiempirical theory) and the other obtaining Nsatγ = 125 (experiment, but on a substituted disordered form of PA!). We report here ab initio calculations up through N = 49 (C98H100) and show that Nsatγ = 45 ± 5. The much larger experimental value, Nsatγ = 125, is explained in terms of the structural defects and disorder introduced by the synthetic method.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::5bdbc847e7ae0182a0336795197920b4 https://doi.org/10.1016/0009-2614(96)00458-7 Zobrazit plný text záznamu Full Text from ScienceDirect