Breakdown of the first hyperpolarizability/bond-length alternation parameter relationship
2010 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 107, no 38, 16453-16458 p.Article in journal (Refereed) Published
We have investigated the dependence of the static first hyperpolarizability on the bond-length alternation (BLA) parameter. Our analysis indicates that the validity of the first hyperpolarizability/BLA parameter relationship is restricted to the no-field, vacuum, limit, while it successively breaks down along with increasing polarity of a surrounding medium, becoming invalid, for instance, in an aqueous solution. This contention is based on a series of TD-DFT, TD-DFT/PCM and hybrid TD-DFT/MM calculations of the first hyperpolarizability for a set of molecular configurations generated from Car-Parrinello hybrid QM/MM simulations of the stilbazolium merocyanine chromophore in chloroform and water solvents, and on a rationalization by means of the two-state model for the first hyperpolarizability. The BLA dependence of the three parameters entering the two-state model is shown to be qualitatively different in vacuum and in solvents. Particularly, in the vacuum case, the difference between ground and excited state dipole moments goes to zero for a vanishing BLA, which is not true in the presence of an aqueous medium. In the aqueous medium, an opposing behavior of the parameters involved in the two-state model results in an almost constant first hyperpolarizability with varying BLA parameter.
Place, publisher, year, edition, pages
2010. Vol. 107, no 38, 16453-16458 p.
bond-length alternation, hybrid QMMM modeling, nonlinear optical materials
IdentifiersURN: urn:nbn:se:kth:diva-26672DOI: 10.1073/pnas.1006572107ISI: 000282003700016ScopusID: 2-s2.0-78049236944OAI: oai:DiVA.org:kth-26672DiVA: diva2:373569
QC 201012012010-12-012010-11-262013-03-14Bibliographically approved