Ab initio Studies on Acene Tetramers : Herringbone Structure

The structures and energetics of the acene tetramers up to pentacene are investigated with the ab initio molecular orbital method at the level of second-order Myller-Plesset perturbation theory (MP2/aug-cc-pVDZ//MP2/3-21G(d)). Herringbone-style structures were optimized as local minima, and the geometrical discrepancy between crystal and MP2 theoretical structure is reasonably small. The binding energy of pentacene tetramer was estimated up to about 90 kcal/mol. The hole transfer integral computed with ab initio geometry shows discrepancy compared to those with solid-state geometry. However, transfer integrals of acenes computed with using the key geometries of pentacene are almost constant value of 0.2eV.