| Abstract
| - Contour plots of bonding orbitals for system 1 are shown. There is an obvious difference in the electronic transition between pentacene and system 1.
- Four isomers formed by a gold atom attached to a pentacene molecule were investigated by densityfunctional theory due to their potential applications in molecular electronics. The aim of our study is toshed light on the bonding nature and interaction between gold and carbon, to estimate the influence ofgold atoms on the electronic spectrum of the pentacene, and to predict second-order nonlinear optical(NLO) properties. The results show that the gold and carbon atom of systems 1 and 2 can form a covalentbond, which has σ single-bond character. However, there are strong donor−acceptor interactions betweengold and carbon of systems 3 and 4. The influence of the number of benzene rings on the bonding natureor interactions is also discussed. Adding a gold atom to the pentacene obviously changes the transitionnature of pentacene and results in an increase in possible transition, especially for systems 3 and 4.These systems possess moderate molecular second-order polarizabilities compared with the organometallicand organic complexes. The β value of system 4 is greater than that of system 1. Thus, subtle variationsin the molecular architecture result in substantial enhancement of the second-order NLO response. Inview of high transparency and the moderate β values, our studied systems could become a kind of potentialsecond-order NLO material.
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