Torsional Potentials and Full-Dimensional Simulation of Electronic Absorption Spectra of para-Phenylenevinylene Oligomers Using Semiempirical Hamiltonians
- Author(s)
- Vladimir Lukes, Roland Solc, Mario Barbatti, Hans Lischka, Harald Kauffmann
- Abstract
A systematic study of torsional potential curves in electronic ground state based on second-order Moller-Plesset energy (MP2), density functional theory (DFT), and Austin mode 1 (AM1) methods is presented for para-phenylenevinylene oligomers constructed from two to four aromatic rings. The semiempirical AM1 approach gives the correct location of potential energy minima in comparison with the reference MP2 calculations and literature data. However, the semiempirical AM1 energy barriers at perpendicular orientation are ca. 30% smaller than the MP2 ones. The DFT calculations indicate optimal planar structures and the barriers are three times higher than MP2 values. Excited-state potential energy curves evaluated from vertical excitations at the time-dependent density functional theory (TD-DFT) and ab initio CI levels exhibit much steeper increase of values in the vicinity of perpendicular orientation than in the semiempirical Zerner's intermediate neglect of differential overlap (ZINDO) and ab initio RI-CC2 cases. The effects of vibrational motion of phenylene rings on the torsional broadening of absorption spectra were estimated from semi-classical molecular dynamics simulations and harmonic oscillator sampling. The simulated spectra agree well with the experiment and allow estimating the conformer distribution of the molecules.
- Organisation(s)
- Department of Theoretical Chemistry, Electronic Properties of Materials
- External organisation(s)
- Slovak University of Technology in Bratislava
- Journal
- Journal of Theoretical & Computational Chemistry
- Volume
- 9
- Pages
- 249-263
- No. of pages
- 15
- ISSN
- 0219-6336
- DOI
- https://doi.org/10.1142/S0219633610005645
- Publication date
- 2010
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103015 Condensed matter, 104022 Theoretical chemistry
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/9944e06e-efa6-4b50-a1c0-015d8660e32e