Accurate prediction of the electronic properties of zigzag graphene nanoribbons (ZGNRs) has been very challenging for conventional electronic structure methods due to the presence of strong static correlation effects. To meet the challenge, we study the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, and symmetrized von Neumann entrop...

In regard to the worldwide interest in synthesis and application of stable carbenes, DFT calculations (B3LYP/6-311++G**//B3LYP/6-31+G* levels) are employed to reach at a series of phenyl carbenes. The singlet-triplet energy separations (ΔES-T), HOMO–LUMO energy gaps (ΔEHOMO-LUMO), as well as philicity indices (N and ω) and basicity of these carbenes are compared and contrasted with the synthesi...

We extend the recently proposed thermally-assisted-occupation density functional theory (TAO-DFT) [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)] to generalized-gradient approximation (GGA) exchange-correlation density functionals. Relative to our previous TAO-LDA (i.e., the local density approximation to TAO-DFT), the resulting TAO-GGAs are significantly superior for a wide range of applicatio...

The decomposition of 1,2-dioxetanone into a CO(2) molecule and into an excited state formaldehyde molecule was studied in condensed phase, using a density functional theory approach. Singlet and triplet ground and excited states were all included in the calculations. The calculations revealed a novel mechanism for the chemiluminescence of this compound. The triplet excitation can be explained b...

The effects of Mg, Zn, Cd, and Pd dications on the photophysical properties of the tetraphenylporphyrin ligand have been explored, considering the corresponding complexes and by using the density functional theory and its time-dependent extension. Results show that absorption wavelengths do not change significantly when the metal ion changes contrary to what happens to the singlet-triplet energ...

Department of Chemistry, Chemical The University of Minnesota, 207 Pleasant St USA. E-mail: [email protected]; cramer@u † Electronic supplementary information gaps for CASSCF(4,4), CASSCF(8,8), D numbers of CSFs with more signica HONO 1, HONO, LUNO and LUNO+1 for gap (kcal mol ) of decacene for DF singlet–triplet energy gap (kcal mol 1 functionals, molecular geometries, a 10.1039/c6sc05036k Cit...

Linear and non-linear optical properties of indeno[2,1-b]fluorene (1) and its structural isomers with 20 π-electrons have been studied using many body methods. As compared to other π electron systems of similar conjugation length, the experimentally measured optical gap (vertical excitation energy) and the singlet-triplet gap of 1 are quite small. The diradical character calculated using the ab...

Carbocations are traditionally thought to be closed-shell electrophiles featuring an empty orbital rich in p character. Here, density functional theory computations indicate that when strong π donors are not placed in direct conjugation with benzylic-type cations, alternative diradical configurations that resemble non-Kekulé diradicals are possible. For certain donor-acceptor frameworks, an ope...

Triplet emitter materials present attractive possibilities for optimizations of organic/organometallic light emitting diodes (OLEDs). This is due to the significantly higher efficiencies obtainable with these compounds as compared to organic emitters. In this contribution, first a schematic introduction is given, how an OLED device is built-up and why multi-layer structures are preferred. Then ...