Naslov
CASSCF/CASPT2 and TD-DFT Study of Valence and Rydberg Electronic Transitions in Fluorene, Carbazole, Dibenzofuran, and Dibenzothiophene

Autori
Ljubić, Ivan ; Sabljić, Aleksandar

Izvornik
Journal of Physical Chemistry A (1089-5639) 115 (2011), 18; 4840-4850

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Ab initio calculations; Multireference calculations; Density functional calculations; UV/Vis spectroscopy; Fluorene heteroanalogs; Spectral assignment

Sažetak
A combination of multireference CASSCF/CASPT2 and time-dependent DFT (TD-B3P86) theoretical treatments was employed to test their predictions against recently proposed assignments of the vacuum-UV spectra of fluorene and its three heteroanalogues — dibenzofuran, carbazole, and dibenzothiophene — up to the ionization threshold. For the low-lying transitions, the theoretically based assignments are generally not problematic because of the well resolved bands, although, even in this region, the two methods yield some opposing predictions. Further on toward the vacuum region, the assignments prove increasingly challenging because of predicted crowding of transitions, many of which exhibit significant intensity. Some of the transitions in this region and beyond—toward the ionization thresholds—are thus necessarily assigned only tentatively. Overall, the two methods are frequently found to complement each other well, and equivalent transitions usually appear as bracketed from the high- (CASPT2) and low- (TD-B3P86) energy sides.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA