Through-Space Higher Dimensionality Conjugation to Enhance Optical Properties? An Exploratory Computational Investigation on a Model System

• Published in: The journal of physical chemistry. B Vol. 102; no. 47; pp. 9378 - 9384
• Main Authors: Xie, Ou, Dirk, Carl W
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.11.1998
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp9818434

AMPAC (Semichem Inc.) AM1 semiempirical calculations on stacked benzene delocalized ring systems suggest that very large third-order polarizabilities (γ) can be obtained. Systems of +2 charge consisting of benzene rings separated by 3 Å display finite-field (FF) zero frequency γ(0;0,0;0)s that are many orders of magnitude larger than any thus far commonly encountered or previously predicted for organics. The ratio of the FF Re{γ} to Re{α} is an increasing function with system size for the +2 species and is a decreasing function for the neutral species. Up to 14 rings, the largest systems currently calculated, there is not yet a clear indication of leveling off or saturation of γ or γ/α. This is discussed in the context of the absence of electron correlation in these SCF-only calculations. The feasibility of such systems is discussed, as well as potentially significant limitations to the calculations that need to be further investigated before the certainty of these predictions can be certified.