Intersystemcrossing and phosphorescence rates in facIr{sup III}(ppy){sub 3}: A theoretical study involving multireference configuration interaction wavefunctions
Abstract
We have employed combined density functional theory and multireference configuration interaction methods including spin–orbit coupling (SOC) effects to investigate the photophysics of the green phosphorescent emitter factris(2phenylpyridine)iridium (facIr(ppy){sub 3}). A critical evaluation of our quantum chemical approaches shows that a perturbational treatment of SOC is the method of choice for computing the UV/Vis spectrum of this heavy transition metal complex while multireference spin–orbit configuration interaction is preferable for calculating the phosphorescence rates. The particular choice of the spin–orbit interaction operator is found to be of minor importance. Intersystem crossing (ISC) rates have been determined by Fourier transformation of the time correlation function of the transition including Dushinsky rotations. In the electronic ground state, facIr(ppy){sub 3} is C{sub 3} symmetric. The calculated UV/Vis spectrum is in excellent agreement with experiment. The effect of SOC is particularly pronounced for the metaltoligand charge transfer (MLCT) band in the visible region of the absorption spectrum which does not only extend its spectral onset towards longer wavelengths but also experiences a blue shift of its maximum. PseudoJahnTeller interaction leads to asymmetric coordinate displacements in the lowest MLCT states. Substantial electronic SOC and a small energy gap make ISC an ultrafast process in facIr(ppy){sub 3}. Formore »
 Authors:
 Institute of Theoretical and Computational Chemistry, HeinrichHeineUniversity Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany)
 Fachbereich Chemie and Forschungszentrum OPTIMAS, Technical University of Kaiserslautern, ErwinSchrödingerStraße 52, 67663 Kaiserslautern (Germany)
 Publication Date:
 OSTI Identifier:
 22416215
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTRA; COMPLEXES; CONFIGURATION INTERACTION; CORRELATION FUNCTIONS; COUPLING; DENSITY FUNCTIONAL METHOD; DIPOLE MOMENTS; ENERGY GAP; FINE STRUCTURE; FOURIER TRANSFORMATION; GROUND STATES; IRIDIUM COMPOUNDS; JAHNTELLER EFFECT; LIGANDS; METHYLENE CHLORIDE; PHOSPHORESCENCE; PYRIDINES; REACTION KINETICS; SPIN; WAVE FUNCTIONS
Citation Formats
Kleinschmidt, Martin, Marian, Christel M., Email: Christel.Marian@hhu.de, and Wüllen, Christoph van. Intersystemcrossing and phosphorescence rates in facIr{sup III}(ppy){sub 3}: A theoretical study involving multireference configuration interaction wavefunctions. United States: N. p., 2015.
Web. doi:10.1063/1.4913513.
Kleinschmidt, Martin, Marian, Christel M., Email: Christel.Marian@hhu.de, & Wüllen, Christoph van. Intersystemcrossing and phosphorescence rates in facIr{sup III}(ppy){sub 3}: A theoretical study involving multireference configuration interaction wavefunctions. United States. doi:10.1063/1.4913513.
Kleinschmidt, Martin, Marian, Christel M., Email: Christel.Marian@hhu.de, and Wüllen, Christoph van. 2015.
"Intersystemcrossing and phosphorescence rates in facIr{sup III}(ppy){sub 3}: A theoretical study involving multireference configuration interaction wavefunctions". United States.
doi:10.1063/1.4913513.
@article{osti_22416215,
title = {Intersystemcrossing and phosphorescence rates in facIr{sup III}(ppy){sub 3}: A theoretical study involving multireference configuration interaction wavefunctions},
author = {Kleinschmidt, Martin and Marian, Christel M., Email: Christel.Marian@hhu.de and Wüllen, Christoph van},
abstractNote = {We have employed combined density functional theory and multireference configuration interaction methods including spin–orbit coupling (SOC) effects to investigate the photophysics of the green phosphorescent emitter factris(2phenylpyridine)iridium (facIr(ppy){sub 3}). A critical evaluation of our quantum chemical approaches shows that a perturbational treatment of SOC is the method of choice for computing the UV/Vis spectrum of this heavy transition metal complex while multireference spin–orbit configuration interaction is preferable for calculating the phosphorescence rates. The particular choice of the spin–orbit interaction operator is found to be of minor importance. Intersystem crossing (ISC) rates have been determined by Fourier transformation of the time correlation function of the transition including Dushinsky rotations. In the electronic ground state, facIr(ppy){sub 3} is C{sub 3} symmetric. The calculated UV/Vis spectrum is in excellent agreement with experiment. The effect of SOC is particularly pronounced for the metaltoligand charge transfer (MLCT) band in the visible region of the absorption spectrum which does not only extend its spectral onset towards longer wavelengths but also experiences a blue shift of its maximum. PseudoJahnTeller interaction leads to asymmetric coordinate displacements in the lowest MLCT states. Substantial electronic SOC and a small energy gap make ISC an ultrafast process in facIr(ppy){sub 3}. For the S{sub 1}↝T{sub 1} nonradiative transition, we compute a rate constant of k{sub ISC} = 6.9 × 10{sup 12} s{sup −1} which exceeds the rate constant of radiative decay to the electronic ground state by more than six orders of magnitude, in agreement with the experimental observation of a subpicosecond ISC process and a triplet quantum yield close to unity. As a consequence of the geometric distortion in the T{sub 1} state, the T{sub 1} → S{sub 0} transition densities are localized on one of the phenylpyridyl moieties. In our best quantum chemical model, we obtain phosphorescence decay times of 264 μs, 13 μs, and 0.9 μs, respectively, for the T{sub 1,I}, T{sub 1,II}, and T{sub 1,III} finestructure levels in dichloromethane (DCM) solution. In addition to reproducing the correct orders of magnitude for the individual phosphorescence emission probabilities, our theoretical study gives insight into the underlying mechanisms. In terms of intensity borrowing from spinallowed transitions, the low emission probability of the T{sub 1,I} substate is caused by the mutual cancellation of contributions from several singlet states to the total transition dipole moment. Their contributions do not cancel but add up in case of the much faster T{sub 1,III} → S{sub 0} emission while the T{sub 1,II} → S{sub 0} emission is dominated by intensity borrowing from a single spinallowed process, i.e., the S{sub 2} → S{sub 0} transition.},
doi = {10.1063/1.4913513},
journal = {Journal of Chemical Physics},
number = 9,
volume = 142,
place = {United States},
year = 2015,
month = 3
}

Uranium atoms excited by laser ablation react with CO in excess neon to produce the novel CUO molecule, which forms distinct Ng complexes (Ng = Ar, Kr, Xe) when the heavier noble gases are added. The CUO(Ng) complexes are identified through CO isotopic and Ng substitution on the neon matrix infrared spectra and by comparison to DFT frequency calculations. The UC and UO stretching frequencies of CUO(Ng) complexes are slightly red shifted from frequencies for the 1S+ CUO ground state, which identifies singlet ground state CUO(Ng) complexes. In solid neon the CUO molecule is also a complex CUO(Ne)n, and themore »

Theoretical investigation of intersystem crossing between the a{sup ~1}A{sub 1} and Χ{sup ~3}B{sub 1} states of CH{sub 2} induced by collisions with helium
Collisional energy transfer between the ground (Χ{sup ~3}B{sub 1}) and first excited (a{sup ~1}A{sub 1}) states of CH{sub 2} is facilitated by strong mixing of the rare pairs of accidentally degenerate rotational levels in the ground vibrational manifold of the a{sup ~} state and the (020) and (030) excited bending vibrational manifolds of the X{sup ~} state. The simplest model for this process involves coherent mixing of the scattering Tmatrix elements associated with collisional transitions within the unmixed a{sup ~} and X{sup ~} states. From previous calculations in our group, we have determined cross sections and roomtemperature rate constants formore » 
Theoretical investigation of intersystem crossing in the cyanonitrene molecule, ^{1}NCN → ^{3}NCN
The NCN diradical is an important intermediate of prompt nitric oxide formation in flames. The mechanism of intersystem crossing (ISC) in the NCN molecule formed via pyrolysis or photolysis of NCN _{3} is of relevance to the interpretation of experiments that utilize NCN _{3} as a precursor for laboratory studies of NCN kinetics. This mechanism has been investigated by means of multireference configuration interaction calculations. From the potential energy surfaces for NCN _{3} dissociation, it was inferred that both thermal and photochemical decomposition initially lead to NCN in its lowest singlet state,more » 
Accurate Bond Energies of Hydrocarbons from Complete Basis Set Extrapolated MultiReference Singles and Doubles Configuration Interaction
Quantum chemistry has become one of the most reliable tools for characterizing the thermochemical underpinnings of reactions, such as bond dissociation energies (BDEs). The accurate prediction of these particular properties (BDEs) are challenging for ab initio methods based on perturbative corrections or coupled cluster expansions of the singledeterminant HartreeFock wave function: the processes of bond breaking and forming are inherently multiconfigurational and require an accurate description of nondynamical electron correlation. To this end, we present a systematic ab initio approach for computing BDEs that is based on three components: (1) multireference single and double excitation configuration interaction (MRSDCI) for themore »