Optoelectronic and excitonic properties of oligoacenes and one-dimensional nanostructures.

Hsieh, Timothy H. ; Wong, Brian M.

Sandia National Laboratories

关键词: 77 Nanoscience And Nanotechnology;    Errors;    Nanostructures;    Excitation;    Functionals;   

DOI  :  10.2172/1002094
RP-ID  :  SAND2010-5687
RP-ID  :  AC04-94AL85000
RP-ID  :  1002094

美国|英语

来源: UNT Digital Library

【 摘 要 】

The optoelectronic and excitonic properties in a series of linear acenes are investigated using range-separated methods within time-dependent density functional theory (TDDFT). In these highly-conjugated systems, we find that the range-separated formalism provides a substantially improved description of excitation energies compared to conventional hybrid functionals, which surprisingly fail for the various low-lying valence transitions. Moreover, we find that even if the percentage of Hartree-Fock exchange in conventional hybrids is re-optimized to match wavefunction-based CC2 benchmark calculations, they still yield serious errors in excitation energy trends. Based on an analysis of electron-hole transition density matrices, we also show that conventional hybrid functionals overdelocalize excitons and underestimate quasiparticle energy gaps in the acene systems. The results of the present study emphasize the importance of a range-separated and asymptotically-correct contribution of exchange in TDDFT for investigating optoelectronic and excitonic properties, even for these simple valence excitations.