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Theoretical study of the longitudinal first hyperpolarizability of polysilaacetylene
Denis Jacquemin1, Eric A Perpete, Jean-Marie Andre
1Laboratoire de Chimie Theorique Appliquee, Facultes Universitaires Notre-Dame de la Paix, B-5000 Namur, Belgium. denis.jacquemin@fundp.ac.be
Abstract:
With the help of ab initio tools taking into account dynamic electron correlation effects, we study the longitudinal electronic first hyperpolarizability of carbon-silicon analogues to polyacetylene. It turns out that the MP2/6-31G(d)//HF/6-31G(d) scheme is suitable to obtain a semiquantitative accuracy for the first hyperpolarizability of long polysilaacetylene oligomers. The conformation of the chain has a crucial impact on its second-order nonlinear optical properties. We also show that, for some chain lengths, the frequency dispersion effects may have a huge impact, even when far away from resonance. These phenomena are rationalized in terms of delocalization and asymmetry.
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