PNNL

Abstract

Coupled-cluster theory with single and double excitations (CCSD) is applied to the calculation of optical properties of large polyaromatic hydrocarbons. Dipole polarizabilities are reported for benzene, pyrene, and the oligoacenes sequence n=2-6. Dynamic polarizabilities were calculated on polyacences as large asa pentacene for a single frequency and for benzene and pyrene at many frequencies. The basis set effect was studied for benzene using a variety of basis sets in the Pople and Dunning families up to aug-cc-pVQZ and the Sadlej p VTZ basis, which was used exclusively for the largest molecules. Optimized geometries were evaluated for some of the compounds using HF, B3LYP, PBE0, MP2 and CCSD to understand the role of bond-length-alteration (BLA). Finally, the polarizability results ere compared to four common density-functionals (B3LYP, BLYP, PBE0, PBE).