On the accurate calculation of polarizabilities and second hyperpolarizabilities of polyacetylene oligomer chains using the CAM-B3LYP density functional

• Published in: The Journal of chemical physics Vol. 130; no. 19; p. 194114
• Main Authors: Limacher, Peter A, Mikkelsen, Kurt V, Lüthi, Hans Peter
• Format: Journal Article
• Language: English
• Published: United States 21.05.2009
• ISSN: 1089-7690
• DOI: 10.1063/1.3139023

The polarizability and second hyperpolarizability of polyacetylene oligomer chains of increasing size up to C(24)H(26) were investigated by means of the Coulomb-attenuating method (CAM-B3LYP) using response theory. It was found that this long-range corrected density functional removes to large parts the overestimation observed for standard methods and in many cases provides results close to those of coupled cluster calculations. A direct comparison to experimentally observed dynamic hyperpolarizabilities is made to estimate the accuracy of the method. A basis set study revealed a noticeable contribution of diffuse orbitals to the hyperpolarizability also for larger oligomers. Furthermore, CAM-B3LYP is also confirmed to provide molecular geometries close to experimentally observed structures, especially for longer chain lengths.