Benchmarking DFT and TD-DFT Functionals for the Ground and Excited States of Hydrogen-Rich Peptide Radicals

2014 ◽  
Vol 10 (8) ◽  
pp. 3308-3318 ◽  
Author(s):  
Vanessa Riffet ◽  
Denis Jacquemin ◽  
Emilie Cauët ◽  
Gilles Frison
Keyword(s):  
Excited States ◽  
Td Dft ◽  
Peptide Radicals

The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)

2003 ◽  
Vol 68 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Stanislav Záliš ◽  
Antonín Vlček ◽  
Chantal Daniel
Keyword(s):  
Excited States ◽  
Substitution Effect ◽  
Electronic Transitions ◽  
Ligand Field ◽  
Metal Carbonyls ◽  
Electron Density Redistribution ◽  
Time Resolved ◽  
Model Complex ◽  
Td Dft ◽  
Time Resolved Infrared Spectroscopy

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.

Spectroscopic trends in a series of Re(I) α-diimine complexes as a function of the antenna/photoisomerizable ligands: a TD-DFT and MS-CASPT2 study

2014 ◽  
Vol 92 (10) ◽  
pp. 979-986 ◽  
Author(s):  
Megumi Kayanuma ◽  
Chantal Daniel ◽  
Etienne Gindensperger
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Density Functional ◽  
Time Dependent ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ligand Charge Transfer ◽  
Td Dft ◽  
Energy Domain ◽  
Diimine Complexes

The absorption spectra of 11 rhenium(I) complexes with photoisomerizable stilbene-like ligands have been investigated by means of density functional theory (DFT). The electronic structures of the ground and excited states were determined for [Re(CO)3(N,N)(L)]+ (N,N = bpy (2,2′-bipyridine), phen (1,10-phenanthroline), Me4phen (3,4,7,8-tetramethyl-1,10-phenanthroline), ph2phen (4,7-diphenyl-1,10-phenanthroline), or Clphen (5-chloro-1,10-phenanthroline); L = bpe (1,2-bis(4-pyrydil)ethylene), stpy (4-styrylpyridine), or CNstpy (4-(4-cyano)styrylpyridine)) at the time–dependent (TD) DFT/CAM-B3LYP level of theory in vacuum and acetonitrile to highlight the effects of both antenna N,N and isomerizable L ligands. The TD-DFT spectra of two representative complexes, namely [Re(CO)3(bpy)(stpy)]+ and [Re(CO)3(phen)(bpe)]+, have been compared with MS-CASPT2 spectra. The TD-DFT spectra obtained in vacuum and acetonitrile agree rather well both with the ab initio and experimental spectra. The absorption spectroscopy of this series of molecules is characterized by the presence of three low-lying metal to ligand charge transfer (MLCT) states absorbing in the visible energy domain. The nature of the isomerizable ligands (bpe, stpy, or CNstpy) and the type of antenna ligands (bpy, phen, and substituted phen) control the degree of mixing between the MLCT and intraligand excited states, their relative energies, as well as their intensities.

scholarly journals Excited-states of a rhenium carbonyl diimine complex: solvation models, spin–orbit coupling, and vibrational sampling effects

2017 ◽  
Vol 19 (40) ◽  
pp. 27240-27250 ◽  
Author(s):  
Sebastian Mai ◽  
Hugo Gattuso ◽  
Maria Fumanal ◽  
Aurora Muñoz-Losa ◽  
Antonio Monari ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Excited States ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Implicit Solvation ◽  
Td Dft ◽  
Rhenium Carbonyl ◽  
Solvation Models ◽  
P Absorption

Absorption spectra of [Re(CO)3(imidazole)(phenanthroline)]+ were computed using TD-DFT with QM/MM, frozen-density embedding, and implicit solvation models.

DFT and TD-DFT study of the enol and thiol tautomers of 3-thioxopropanal in the ground and first singlet excited states

2017 ◽  
Vol 16 (04) ◽  
pp. 1750034 ◽  
Author(s):  
Kolsoom Shayan ◽  
Alireza Nowroozi
Keyword(s):  
Excited States ◽  
Ground State ◽  
Global Minimum ◽  
Substitution Effects ◽  
Structure Stability ◽  
Stable Form ◽  
Orbital Parameters ◽  
Td Dft ◽  
Intramolecular Hydrogen ◽  
Linear Correlations

In the first part of this paper, a comprehensive theoretical study of molecular structure, stability, intramolecular hydrogen bond (IMHB) and [Formula: see text]-electron delocalization ([Formula: see text]-ED) of the enol and thiol tautomers of 3-thioxopropanal (TPA) in the ground state is performed. In this regard, all of the plausible conformations of TPA at M06-2X/6-311[Formula: see text]G(d,p) are optimized and a variety of theoretical levels are employed to identify the global minimum. Our calculations show that E1 is the most stable form that is in contrast to the results of Gonzalez et al. [J Phys Chem 101: 9710, 1997]. In order to elucidate this duality, the IMHB and [Formula: see text]-ED of chelated forms (E1 and T1) have been extensively investigated. So, it is found that both of the IMHB analysis and [Formula: see text]-ED concepts emphasize on the E1, as the global minimum. In the second part of this study, a set of simple electron-withdrawing and electron-donating substituents such as CN, F, Cl, CH3 and NH2 have been considered to evaluate their effects on the IMHB of the first singlet excited state of E1 and T1 at TD-DFT/6–311[Formula: see text]G(d,p) level of theory. According to our analysis, it was found that the IMHB strength of the excited states are much weaker than the ground states. Surprisingly, the IMHB of thiol derivatives is stronger than the enol ones in contrast to the ground state. Furthermore, the substitution effects in the ground and excited states are significantly different. Finally, various linear correlations between the IMHB energies with geometrical, topological and molecular orbital parameters are obtained.

TD-DFT calculations of the excited states of metalloporphyrins relevant to organic solar photovoltaic cells

2014 ◽  
Vol 18 (06) ◽  
pp. 475-492 ◽  
Author(s):  
Neha Agnihotri ◽  
Ronald P. Steer
Keyword(s):  
Dft Calculations ◽  
Electronic State ◽  
Excited States ◽  
Photovoltaic Cells ◽  
Oscillator Strengths ◽  
Solar Photovoltaic ◽  
Dft Methods ◽  
Radiative Transitions ◽  
Td Dft ◽  
Triplet Excited States

The molecular orbital energies and symmetries, electronic state energies and symmetries, and orbital compositions and oscillator strengths for one-photon radiative transitions up to an energy of 4 eV have been calculated by DFT and TD-DFT methods for 15 d0 and d10 metalloporphyrins. Data for both singlet and triplet excited states are reported and used to identify potential candidates for use as photon upconverters by homomolecular triplet–triplet annihilation.

scholarly journals Macroscopic quantum electrodynamics and density functional theory approaches to dispersion interactions between fullerenes

2020 ◽  
Vol 22 (40) ◽  
pp. 23295-23306
Author(s):  
Saunak Das ◽  
Johannes Fiedler ◽  
Oliver Stauffert ◽  
Michael Walter ◽  
Stefan Yoshi Buhmann ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited States ◽  
Quantum Electrodynamics ◽  
Density Functional ◽  
Dispersion Interactions ◽  
Functional Theory ◽  
Electronically Excited States ◽  
Macroscopic Quantum ◽  
Td Dft ◽  
Electronically Excited

Van der Waals potentials determine supramolecular structures of molecules in ground and long-lived electronically excited states. We investigate how macroscopic quantum electrodynamics can be used to efficiently describe such potentials based on (TD)DFT-derived polarizabilities.

scholarly journals Towards Iron(II) Complexes with Octahedral Geometry: Synthesis, Structure and Photophysical Properties

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5991
Author(s):  
Mohamed Darari ◽  
Antonio Francés-Monerris ◽  
Bogdan Marekha ◽  
Abdelatif Doudouh ◽  
Emmanuel Wenger ◽  
...  
Keyword(s):  
Excited States ◽  
Photophysical Properties ◽  
Octahedral Geometry ◽  
Ligand Field ◽  
Unexpected Result ◽  
Quintet State ◽  
Dft Modeling ◽  
Ligand Charge Transfer ◽  
Td Dft ◽  
Polypyridine Complexes

The control of ligand-field splitting in iron (II) complexes is critical to slow down the metal-to-ligand charge transfer (MLCT)-excited states deactivation pathways. The gap between the metal-centered states is maximal when the coordination sphere of the complex approaches an ideal octahedral geometry. Two new iron(II) complexes (C1 and C2), prepared from pyridylNHC and pyridylquinoline type ligands, respectively, have a near-perfect octahedral coordination of the metal. The photophysics of the complexes have been further investigated by means of ultrafast spectroscopy and TD-DFT modeling. For C1, it is shown that—despite the geometrical improvement—the excited state deactivation is faster than for the parent pseudo-octahedral C0 complex. This unexpected result is due to the increased ligand flexibility in C1 that lowers the energetic barrier for the relaxation of 3MLCT into the 3MC state. For C2, the effect of the increased ligand field is not strong enough to close the prominent deactivation channel into the metal-centered quintet state, as for other Fe-polypyridine complexes.

Tuning Excited States of Bipyridyl Platinum(II) Chromophores with π-Bonded Catecholate Organometallic Ligands: Synthesis, Structures, TD-DFT Calculations, and Photophysical Properties

2014 ◽  
Vol 53 (13) ◽  
pp. 6624-6633 ◽  
Author(s):  
Jamal Moussa ◽  
Lise-Marie Chamoreau ◽  
Alessandra Degli Esposti ◽  
Maria Pia Gullo ◽  
Andrea Barbieri ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Photophysical Properties ◽  
Td Dft

Luminescence properties and optimized structural conformations of the S0, S1 and T1 states of a tetranuclear formamidinate complex based on AuI and AgI metal ions

2019 ◽  
Vol 75 (7) ◽  
pp. 985-989
Author(s):  
Wayne Hsu
Keyword(s):  
Metal Ions ◽  
Excited States ◽  
Ground State ◽  
Density Functional ◽  
Metal Salts ◽  
Time Dependent ◽  
Functional Theory ◽  
Planar Conformation ◽  
Ligand Charge Transfer ◽  
Td Dft

N,N′-Bis(pyridin-4-yl)formamidine (4-pyfH) was reacted with AuI and AgI metal salts to form a novel tetranuclear complex, tetrakis[μ-N,N′-bis(pyridin-4-yl)formamidinato]digold(I)disilver(I), [Ag2Au2(C11H9N4)2] or [Au x Ag4–x (4-pyf)4] (x = 0–4), 1, which is supported by its metallophilicity. Due to the potential permutation of the coordinated metal ions, six different canonical structures of 1 can be obtained. Complex 1 shows an emission at 501 nm upon excitation at 375 nm in the solid state and an emission at 438 nm upon excitation at 304 nm when dispersed in methanol. Time-dependent density functional theory (TD-DFT) calculations confirmed that these emissions can be ascribed to metal-to-ligand charge transfer (MLCT) processes. Moreover, the calculations of the optimized structural conformations of the S0 ground state, and the S1 and T1 excited states are discussed and suggest a distorted planar conformation for the tetranuclear Au2Ag2 complex.

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