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Showing papers in "Journal of Physical Chemistry A in 1999"


Journal ArticleDOI
TL;DR: In this article, temperature-programmed reaction studies of the catalyzed combustion of CO on size-selected small monodispersed Aun (n ≤ 20) gold clusters supported on magnesia, and first-principle simulations reveal the microscopic origins of the observed unusual catalytic activity, with Au8 being the smallest catalytically active size.
Abstract: While inert as bulk material, nanoscale gold particles dispersed on oxide supports exhibit a remarkable catalytic activity. Temperature-programmed reaction studies of the catalyzed combustion of CO on size-selected small monodispersed Aun (n ≤ 20) gold clusters supported on magnesia, and first-principle simulations, reveal the microscopic origins of the observed unusual catalytic activity, with Au8 found to be the smallest catalytically active size. Partial electron transfer from the surface to the gold cluster and oxygen-vacancy F-center defects are shown to play an essential role in the activation of nanosize gold clusters as catalysts for the combustion reaction.

1,355 citations


Journal ArticleDOI
TL;DR: The newest version of the GROningen MOlecular Simulation program package, GROMOS96, has been developed for the dynamic modelling of (bio)molecules using the methods of molecular dynamics, stochastic dynamics, and energy minimization as well as the path-integral formalism.
Abstract: We present the newest version of the GROningen MOlecular Simulation program package, GROMOS96. GROMOS96 has been developed for the dynamic modelling of (bio)molecules using the methods of molecular dynamics, stochastic dynamics, and energy minimization as well as the path-integral formalism. An overview of its functionality is given, highlighting methodology not present in the last major release, GROMOS87. The organization of the code is outlined, and reliability, testing, and efficiency issues involved in the design of this large (73 000 lines of FORTRAN77 code) and complex package are discussed. Finally, we present two applications illustrating new functionality: local elevation simulation and molecular dynamics in four spatial dimensions.

1,290 citations


Journal ArticleDOI
TL;DR: The electron pair density, in conjunction with the definition of an atom in a molecule, enables one to determine the average number of electron pairs that are localized to each atom and the number that are formed between any given pair of atoms as mentioned in this paper.
Abstract: The electron pair density, in conjunction with the definition of an atom in a molecule, enables one to determine the average number of electron pairs that are localized to each atom and the number that are formed between any given pair of atoms. Thus, it is through the pair density that the Lewis model of electronic structure finds physical expression. The pairing of electrons is a consequence of the Pauli principle whose effect is made manifest through the creation of the Fermi hole. The density describing the spatial distribution of the Fermi hole for an electron of given spin determines how the density of that electron is spread out in space, excluding an equivalent amount of same-spin density. The averaging of the Fermi density over single atoms or pairs of atoms determines the corresponding contributions to the total Fermi correlation. It is these terms that yield the localization and delocalization indices that determine the intra- and interatomic distribution of electron pairs that enables one to c...

918 citations


Journal ArticleDOI
TL;DR: A reduced HOMO−LUMO gap is defined as the energy separation of a molecule divided by that of the hypothetical polyene reference, which is used as an index of kinetic stability for a variety of polycyclic aromatic hydrocarbons (PAHs) as mentioned in this paper.
Abstract: A reduced HOMO−LUMO gap, which is defined as the HOMO−LUMO energy separation of a molecule divided by that of the hypothetical polyene reference, can be used as an index of kinetic stability for a variety of polycyclic aromatic hydrocarbons (PAHs). The reduced HOMO−LUMO gap < 1.00 indicates that the HOMO contributes to the decrease in the topological resonance energy. In general, PAHs with reduced HOMO−LUMO gaps < 1.30 are chemically very reactive. Fully benzenoid hydrocarbons are kinetically very stable with very large reduced HOMO−LUMO gaps. Many of the PAH molecules with large reduced HOMO−LUMO gaps are closed-shell substructures of nonmetallic one-dimensional benzenoid polymers.

709 citations


Journal ArticleDOI
TL;DR: The rotational correlation times of individual asphaltene molecules have been determined using fluorescence depolarization techniques, addressing an active, long-standing controversy as discussed by the authors, using simple...
Abstract: The rotational correlation times of individual asphaltene molecules have been determined using fluorescence depolarization techniques, addressing an active, long-standing controversy. Using simple ...

499 citations


Journal ArticleDOI
TL;DR: In this paper, the shape transformation of gold nanorods in micellar solution by exposure to laser pulses of different pulse width (100 fs and 7 ns) and different energies (μJ to mJ) at 800 nm was studied.
Abstract: We studied the shape transformation (by use of TEM and optical absorption spectroscopy) of gold nanorods in micellar solution by exposure to laser pulses of different pulse width (100 fs and 7 ns) and different energies (μJ to mJ) at 800 nm, where the longitudinal surface plasmon oscillation of the nanorods absorb At moderate energies, the femtosecond irradiation melts the nanorods to near spherical particles of comparable volumes while the nanosecond pulses fragment them to smaller near-spherical particles At high energies, fragmentation is also observed for the femtosecond irradiation A mechanism involving the rate of energy deposition as compared to the rate of electron−phonon and phonon−phonon relaxation processes is proposed to determine the final fate of the laser-exposed nanorods, ie, melting or fragmentation

479 citations


Journal ArticleDOI
TL;DR: In this article, the complex dielectric permittivity of aqueous sodium chloride solutions has been determined in the frequency range 0.2 ≤ v(GHz) ≤ 20 with a commercial dielectrics measurement system based on a vector network analyzer.
Abstract: The complex dielectric permittivity of aqueous sodium chloride solutions has been determined in the frequency range 0.2 ≤ v(GHz) ≤ 20 with a commercial dielectric measurement system based on a vector network analyzer. NaCl solutions 0.1 ≤ m (mol kg-1) ≤ 5 (mass fraction 0.005 ≤ w ≤ 0.23) were investigated at 5, 20, 25, and 35°C. An improved calibration procedure of the dielectric measurement system for conducting samples was developed. The complex permittivity spectra have been represented by a Cole-Cole relaxation time distribution. Where possible, the obtained fitting parameters, static permittivity ∈ and relaxation time τ, and distribution parameter a, are compared with literature data to assess the performance of the instrument, which was found to be comparable to that of time domain and waveguide systems. Effective solvation numbers were deduced from the effect of NaCl concentration on ∈. The data suggest that in addition to the irrotational bonding of water molecules by Na+ ions, kinetic depolarization under slip boundary conditions determines the solution permittivity. A three-state model is proposed to describe the concentration dependence of τ. © Copyright 1999 by the American Chemical Society.

449 citations


Journal ArticleDOI
TL;DR: In this paper, the authors discuss the recent theoretical developments that have led to these advances and demonstrate in a series of benchmark calculations the present capabilities of state-of-the-art computational quantum chemistry programs for the prediction of molecular structure and properties.
Abstract: Recent advances in linear scaling algorithms that circumvect the computational bottlenecks of large-scale electronic structure simulations make it possible to carry out density functional calculations with Gaussian orbitals on molecules containing more than 1000 atoms and 15 000 basis functions using current workstations and personal computers. This paper discusses the recent theoretical developments that have led to these advances and demonstrates in a series of benchmark calculations the present capabilities of state-of-the-art computational quantum chemistry programs for the prediction of molecular structure and properties.

408 citations


Journal ArticleDOI
TL;DR: The development of a smooth solvation potential from which analytic derivatives can be derived is important for molecular applications that require geometry optimization and conformational sampling as discussed by the authors, and the development of such a potential can be found in the literature.
Abstract: The development of a smooth solvation potential from which analytic derivatives can be derived is important for molecular applications that require geometry optimization and conformational sampling...

364 citations


Journal ArticleDOI
TL;DR: In this article, the photoluminescence from films of a soluble phenylenevinylene polymer has been investigated and it is shown unambiguously that there is long-lived emission in this material due to excimers and estimate that the quantum yield for excimer formation is as high as 50%.
Abstract: We report measurements of photoluminescence from films of a soluble phenylenevinylene polymer that has prospective importance as the emissive material in light-emitting diodes We show unambiguously that there is long-lived emission in this material due to excimers and estimate that the quantum yield for excimer formation is as high as 50% Since excimers in this polymer largely decay nonradiatively at ambient temperature, their prominence serves to drastically reduce the possible efficiency of electroluminescent conjugated polymer devices

356 citations


Journal ArticleDOI
TL;DR: In this article, the translational self-diffusion coefficients of supercooled water at atmospheric pressure were examined using pulsed-gradient spin-echo NMR diffusion measurements down to 238 K.
Abstract: The translational self-diffusion coefficients of supercooled water at atmospheric pressure were examined using pulsed-gradient spin−echo NMR diffusion measurements down to 238 K. As the temperature decreased, the diffusion behavior became distinctly non-Arrhenius. It was found that the diffusion behavior when plotted in an Arrhenius form was well-described by a Vogel−Tamman−Fulcher-type relationship in the temperature range from 298 to about 242 K. However, a fractional power-law-type equation was found to provide a better fit that extended over the entire measured temperature range. Below this temperature range, the diffusion coefficient decreased rather steeply, and at 238 K, the diffusion coefficient was 1.58 × 10-10 m2 s-1, the lowest value of the water diffusion coefficient so far determined. At this temperature the activation energy for the diffusion was found to be of the order of 44.4 kJ mol-1. The data presented here should allow theoretical models of water to be more stringently tested.

Journal ArticleDOI
TL;DR: In this article, a theoretical model relating the kinetic, mechanistic and thermodynamics aspects of a chemical reaction is presented, based on the consistency between the principle of maximum hardness and the Hammond postulate, and it is used to obtain insights about the reaction mechanisms and to define rate constants in terms of the chemical potential and hardness of activation.
Abstract: A theoretical model relating the kinetic, mechanistic, and thermodynamics aspects of a chemical reaction is presented. The model is based upon the consistency between the principle of maximum hardness and the Hammond postulate, and it is used to obtain insights about the reaction mechanisms and to define rate constants in terms of the chemical potential and hardness of activation. An important result is that when both electronic properties are allowed to vary along the reaction coordinate, it is found that the activation process is controlled by the change in chemical potential while the relaxation one is controlled by the change in hardness.

Journal ArticleDOI
TL;DR: In this article, the present state of research on small dications, dianions, and trications is described, with emphasis on thermochemically stable, multiply charged ions, with small trications in particular.
Abstract: Experimental and computational studies of small, multiply charged ions are of topical interest in chemistry and physics. Moreover, the increasing use of multiply charged ions in the analysis of environmental and biological samples calls for an improvement of the understanding of the fundamental properties of multiply charged ions at a molecular level. Mass spectrometric techniques in conjunction with advanced theoretical studies provide detailed insight into these aspects. This feature article describes the present state of research on small dications, dianions, and trications. Emphasis is given to thermochemically stable, multiply charged ions, with small trications in particular.

Journal ArticleDOI
TL;DR: In this paper, the authors discuss computational methods for carrying out correlated ab initio electronic structure calculations for large systems, focusing on two types of methods: density functional theory (DFT) and localized orbital methods such as local MP2 (LMP2).
Abstract: We discuss computational methods for carrying out correlated ab initio electronic structure calculations for large systems. The focus is on two types of methods: density functional theory (DFT) and localized orbital methods such as local MP2 (LMP2) and a multireference version based upon a generalized valence bond reference wave function, GVB-LMP2. The computational performance of both approaches using pseudospectral numerical methods is documented, and calculated thermochemical and conformational energetics are compared to experimental data.

Journal ArticleDOI
TL;DR: In this article, the performance of various density functional approaches for the calculation of electron paramagnetic resonance (EPR) hyperfine coupling constants in transition metal complexes has been evaluated critically by comparison with experimental data and high-level coupled-cluster results for 21 systems, representing a large variety of different electronic situations.
Abstract: The performance of various density functional approaches for the calculation of electron paramagnetic resonance (EPR) hyperfine coupling constants in transition metal complexes has been evaluated critically by comparison with experimental data and high-level coupled-cluster results for 21 systems, representing a large variety of different electronic situations. While both gradient-corrected and hybrid functionals allow the calculation of isotropic metal hyperfine coupling constants to within ca. 10−15% for the less critical cases (e.g., ScO, TiN, TiO, VO, MnO, MnF), none of the functionals investigated performs well for all complexes. Gradient-corrected functionals tend to underestimate the important core−shell spin polarization. While this may be improved by exact-exchange mixing in some cases, the accompanying spin contamination may even lead to a deterioration of the results for other complexes. We also identify cases, where essentially none of the functionals performs satisfactorily. In the absence of...

Journal ArticleDOI
TL;DR: In this paper, a theoretical analysis of 2D correlation and relaxation experiments is presented for a system consisting of two electronic states each having two or more sublevels, and the separation between absorption and dispersion mode 2D spectra in these experiments is investigated in detail for nonzero pulse duration and compared to related 2D NMR experiments based on a nonlinear optical definition of coherence order.
Abstract: Hybl et al. demonstrated a technique for recording two-dimensional Fourier transform electronic correlation and relaxation spectra based on detecting phase modulation of the signal electric field in a noncollinear femtosecond four-wave mixing experiment. A theoretical analysis of 2D correlation and relaxation experiments is presented for a system consisting of two electronic states each having two or more sublevels. The separation between absorption and dispersion mode 2D spectra in these experiments is investigated in detail for nonzero pulse duration and compared to related 2D NMR experiments based on a nonlinear optical definition of coherence order. Phase-twisted peaks, which mix absorption and dispersion line shapes, can occur under some circumstances. A 1D projection of the complex 2D spectrum is shown to equal the transient grating signal field, and the real part of this projection is related to the spectrally resolved pump−probe signal. Calculated 2D spectra for a two-level Bloch model, an underda...

Journal ArticleDOI
TL;DR: In this paper, the vibrational spectrum of urea was interpreted by measuring the solid state infrared spectra of eight isotopomers of Urea at room temperature and at −196 °C.
Abstract: Although a lot of work has been done on the vibrational analysis of urea, there still remain some contradictions and uncertainties, mainly due to interpretation of the vibrational spectrum of crystalline urea based on force field calculations on isolated urea instead of on urea in its crystal phase. We have shown that this approach is not allowed in the case of urea. The vibrational spectrum of urea was interpreted by measuring the solid state infrared spectra of eight isotopomers of urea at room temperature and at −196 °C, and Raman spectra at room temperature and at −120 °C, and of a urea−water solution. Force field calculations from our recently published article on isolated urea and on urea in its crystal structure, at the Hartree−Fock level with a 6-31++G** basis set, were also used. We have also shown that high-pressure measurements using a “diamond anvil cell” are not useful by performing a vibrational analysis.

Journal ArticleDOI
TL;DR: In this paper, the hole transport energy in the ionization process of organic amines and the electron attaching process of amine cation radicals are evaluated with AM1, ab initio MO, and DFT methods, where dimethylaniline, methyldiphenylamine, and triphenylamines are adopted as a model of a hole transport material.
Abstract: Reorganization energy (λ1) in the ionization process of organic amines and that (λ2) of the electron attaching process of amine cation radicals are evaluated with AM1, ab initio MO, and DFT methods, where dimethylaniline, methyldiphenylamine, and triphenylamine are adopted as a model of a hole transport material. The total λ value (=λ1 + λ2) decreases in the order dimethylaniline > methyldiphenylamine > triphenylamine, which agrees well with an increasing order of experimentally reported hole transport mobility of diamines that are dimers of above-mentioned amines, N,N‘-tetraphenyl-[1,1‘-biphenyl]-4,4‘-diamine < N,N‘-dimethyl-N,N‘-diphenyl-[1,1‘-biphenyl]-diamine < N,N‘-tetramethyl-[1,1‘-biphenyl]-4,4‘-diamine. This relation is reasonably explained with Marcus theory, since the λ value is directly related to the activation energy of hole transfer from one amine cation radical to a neighboring neutral amine, according to Marcus theory. The geometry changes in the ionization process are inspected to find a ...

Journal ArticleDOI
TL;DR: In this paper, three procedures for incorporating higher level electronic structure data into reaction path dynamics calculations are tested, denoted as interpolated optimized energies (IOE), interpolated single-point energies (ISPE), and interpolated interpolated optimization of the reaction path.
Abstract: Three procedures for incorporating higher level electronic structure data into reaction path dynamics calculations are tested. In one procedure, variational transition state theory with interpolated single-point energies, which is denoted VTST-ISPE, a few extra energies calculated with a higher level theory along the lower level reaction path are used to correct the classical energetic profile of the reaction. In the second procedure, denoted variational transition state theory with interpolated optimized corrections (VTST-IOC), which we introduced earlier, higher level corrections to energies, frequencies, and moments of inertia are based on stationary-point geometries reoptimized at a higher level than the reaction path was calculated. The third procedure, called interpolated optimized energies (IOE), is like IOC except it omits the frequency correction. Three hydrogen-transfer reactions, CH3 + H‘H → CH3H‘ + H (R1), OH + H‘H → HOH‘ + H (R2), and OH + H‘CH3 → HOH‘ + CH3 (R3), are used to test and validat...

Journal ArticleDOI
TL;DR: In this article, a variety of molecules containing C−H, N−H and O−H bonds using density functional theory with the B3LYP was computed using B3LYP.
Abstract: Bond dissociation energies, electron affinities, and proton affinities are computed for a variety of molecules containing C−H, N−H, O−H, and S−H bonds using density functional theory with the B3LYP...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the heterogeneous reactivity of gaseous nitrogen dioxide on mineral oxide particles and showed that the surface becomes populated with surface nitrate bonded in several different bonding coordinations (monodentate, bidentate and bridging).
Abstract: The heterogeneous reactivity of gaseous nitrogen dioxide on mineral oxide particles was investigated. In particular, spectroscopic and kinetic measurements have been made to investigate surface reactions of NO2 on Al2O3, Fe2O3, and TiO2 at 298 K. Both gas-phase and surface-bound products are formed from the reaction of NO2 with these mineral oxide particles. At low coverages, FT-IR spectra of the mineral oxide surface exposed to gaseous NO2 show absorptions due to surface nitrite, specifically a chelating nitrito species. As the coverage increases, the surface becomes populated with surface nitrate bonded in several different bonding coordinations (monodentate, bidentate, and bridging). The predominant gas-phase product is NO, although there is a small amount (<1%) of detectable N2O. A Knudsen cell reactor coupled to a quadrupole mass spectrometer was used to measure the uptake coefficient, γ, for NO2 on these oxide particles and to characterize gas-phase product formation. The Knudsen cell data showed NO...

Journal ArticleDOI
TL;DR: In this paper, the authors showed that the erroneous behavior of the density functionals for exchange may lead to wrong predictions for ground-state structures of systems with a three-electron bond.
Abstract: Correlated calculations show the proton-transferred OH−H3O+ isomer to be the ground-state structure of the (H2O)2+ dimer ion, with the C2h hemibond structure being ca. 8 kcal/mol less stable. Modern density functionals however favor the hemibond structure, overestimating the strength of the three-electron bond by ca. 17 kcal/mol. The wrong prediction of the relative stability of the two isomers is attributed to overestimation by the exchange functionals of the self-interaction part of the exchange energy in the hemibond ion due to its delocalized electron hole. It is cautioned that this erroneous behavior of the density functionals for exchange, if unrecognized, may lead to wrong predictions for ground-state structures of systems with a three-electron bond.

Journal ArticleDOI
TL;DR: In this article, a method for evaluating second-order Moller−Plesset (MP2) energy and gradients for solvated molecules described within the polarizable continuum model (PCM) is presented.
Abstract: We present a method for evaluating second-order Moller−Plesset (MP2) energy and gradients for solvated molecules described within the polarizable continuum model (PCM). The explicit inclusion of solvent effects into the evaluation of the relaxed MP2 density through the Z-vector technique is reported and analyzed. Applications to some one-electron response properties (dipoles, electrostatic molecular potentials, electric field gradients) as well as nuclear gradients are presented.

Journal ArticleDOI
TL;DR: In this article, the effects of photoinduced intramolecular charge transfer on the electronic and molecular properties of a series of differently twisted 4-N,N-dimethylamino-4'-cyanobiphenyls are investigated by steady-state and time-resolved fluorescence.
Abstract: This photophysical study addresses the general question of how electron transfer in bichromophoric molecules influences the conformational relaxation, which can be toward either more or less π-conjugation. The effects of photoinduced intramolecular charge transfer on the electronic and molecular properties of a series of differently twisted 4-N,N-dimethylamino-4‘-cyanobiphenyls are investigated by steady-state and time-resolved fluorescence. The dipole moments, radiative rates, and torsional relaxations in the excited state are analyzed by comparison with the absorption spectra and interannular twist angle (φ)-dependent CNDO/S calculations. Independent of the twist angle φ and solvent polarity, the first excited singlet state of these donor−acceptor (D−A) biphenyls (I−III) is an emissive intramolecular 1CT state of the 1La-type transferring charge from the dimethylaminobenzene (D) to the cyanobenzene (A) subunit. Similar to the planar restricted D−A fluorene I, the flexible D−A biphenyl II shows only a we...

Journal ArticleDOI
TL;DR: In this article, the electron density of C−H···π complexes has been determined for a series of H−Hπ complexes, which exhibit either anti-H bond or normal H bond character.
Abstract: The theory of atoms in molecules is used to examine the nature of anti-hydrogen bond (anti-H bond) interaction. Contrary to what is found in normal hydrogen bond (H bond) complexes, which are characterized by lengthening of the X−H bond and a red shift of its stretching frequency, the anti-H bond leads to a shortening of the X−H bond length and a blue shift of its vibrational frequency. The topological properties of the electron density have been determined for a series of C−H···π complexes, which exhibit either anti-H bond or normal H bond character, as well as for the complexes C6H5F···HCCl3 and C6H6···HF, which are representative cases of anti- and normal H bonds. Inspection of the set of topological criteria utilized to characterize conventional H bonds shows no relevant difference in the two classes of H···π complexes. Analysis of the results suggests that the specific features of the anti-H bond originates from the redistribution of electron density in the C−H bond induced upon complexation, which i...

Journal ArticleDOI
TL;DR: In this article, the authors discuss several schemes for obtaining approximate quantum time correlation functions using as input only the corresponding classical results, and assess the merits of each scheme by considering three exactly solvable model problems.
Abstract: The accurate numerical calculation of general quantum time correlation functions for many-body systems is not possible at present We discuss several schemes for obtaining approximate quantum time correlation functions using as input only the corresponding classical results, and assess the merits of each scheme by considering three exactly solvable model problems We then turn to the problem of the vibrational energy relaxation of a high-frequency oscillator in a liquid, where the relaxation rate constant can be related to a certain quantum force−force time correlation function Focusing specifically on the case of liquid oxygen, we calculate the classical force−force time correlation function using a molecular dynamics simulation and then determine various approximations to the relaxation rate constant by applying the schemes considered earlier The Egelstaff scheme is found to lead to reasonable agreement with experiment

Journal ArticleDOI
TL;DR: In this article, femtosecond visible electronic absorption spectroscopy was used to identify an optical marker for the thermalized (and hence fully intraligand delocalized) excited state.
Abstract: The transition metal complexes [Ru(dmb)3]2+ and [Ru(dpb)3]2+, where dmb is 4,4‘-dimethyl-2,2‘-bipyridine and dpb is 4,4‘-diphenyl-2,2‘-bipyridine, have been studied by femtosecond visible electronic absorption spectroscopy. Spectroelectrochemical measurements in conjunction with nanosecond time-resolved absorption spectroscopy allow for the assignment of various features in the excited-state differential absorption spectra as both ligand-based π* ← π* and ligand-to-metal charge transfer (LMCT) in nature. A unique absorptive feature centered at ∼ 530 nm in [Ru(dpb)3]2+ was identified as an optical marker for the thermalized (and hence fully intraligand delocalized) excited state. Single wavelength and full spectrum transient absorption data were obtained on both molecules in CH3CN solution at room temperature following metal-to-ligand charge transfer (MLCT) excitation at 400 nm. Data on [Ru(dmb)3]2+ at 532 nm, a region of net excited-state absorption, revealed biphasic decay kinetics (∼120 fs and 5 ps) att...

Journal ArticleDOI
TL;DR: In this paper, the heat of formation for 49 tetrazole derivatives was calculated with the density functional theory (DFT) B3LYP method by means of designed isodemic and isogyric reactions.
Abstract: The heats of formation (HOF) for 49 tetrazole derivatives are calculated with the density functional theory (DFT) B3LYP method by means of designed isodemic and isogyric reactions. The average abso...

Journal ArticleDOI
TL;DR: Connection atoms are proposed as an alternative to link atoms in semi-empirical hybrid calculations that divide a system at a C−C single bond into a quantum mechanical (QM) and a molecular mechanica as discussed by the authors.
Abstract: Connection atoms are proposed as an alternative to link atoms in semiempirical hybrid calculations that divide a system at a C−C single bond into a quantum mechanical (QM) and a molecular mechanica...

Journal ArticleDOI
TL;DR: In this article, the first time-dependent density functional theory (TDDFT) calculations on the spectra of molecules containing transition metals are reported, and three prototype systems are considered, of which the assignments are controversial:
Abstract: The first time-dependent density functional theory (TDDFT) calculations on the spectra of molecules containing transition metals are reported. Three prototype systems are considered, of which the assignments are controversial: MnO4-, Ni(CO)4, and Mn2(CO)10. The TDDFT results are shown to be comparable in accuracy to the most elaborate ab initio calculations and lead to new insights in the spectra of these molecules. In some cases, the presented TDDFT results differ substantially, in both the ordering and the values for the excitation energies, from the older DFT method for the calculation of excitation energies: the ΔSCF approach. For the Mn2(CO)10 molecule, the presented results are the highest-level theoretical results published so far. Over all, the results show that TDDFT can be a very useful tool in the calculation and interpretation of the spectra of transition metal compounds.