scholarly journals Light-Induced Control of the Spin Distribution on Cu–Dithiolene Complexes: A Correlated Ab Initio Study

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1088 ◽  
Author(s):  
Jhon Zapata-Rivera ◽  
Carmen Calzado
Keyword(s):  
Excited States ◽  
Electronic Structures ◽  
Crystal Packing ◽  
Building Blocks ◽  
Electronic Transitions ◽  
Ab Initio Study ◽  
Spin Distribution ◽  
Conducting Materials ◽  
Dmit Ligand ◽  
Adequate Analysis

Metal dithiolene complexes—M(dmit)2—are key building blocks for magnetic, conducting, and optical molecular materials, with singular electronic structures resulting from the mixing of the metal and dmit ligand orbitals. Their use in the design of magnetic and conducting materials is linked to the control of the unpaired electrons and their localized/delocalized nature. It has been recently found that UV–Vis light can control the spin distribution of some [Cu(dmit)2]−2 salts in a direct and reversible way. In this work, we study the optical response of these salts and the origin of the differences observed in the EPR spectra under UV–Vis irradiation by means of wave function-based quantum chemistry methods. The low-lying states of the complex have been characterized and the electronic transitions with a non-negligible oscillator strength have been identified. The population of the corresponding excited states promoted by the UV–Vis absorption produces significant changes in the spin distribution, and could explain the changes observed in the system upon illumination. The interaction between neighbor [Cu(dmit)2]−2 complexes is weakly ferromagnetic, consistent with the relative orientation of the magnetic orbitals and the crystal packing, but in disagreement with previous assignments. Our results put in evidence the complex electronic structure of the [Cu(dmit)2]−2 radical and the relevance of a multideterminantal approach for an adequate analysis of their properties.

scholarly journals Energetic Degeneracy and Electronic Structures of Germanium Trimers Doped with Titanium

2020 ◽  
Author(s):  
Le Nhan Pham ◽  
Salvy P. Russo
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Electronic Transitions ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Experimental Group ◽  
Comparison With Experimental Data

Several quantum chemical methods including CASSCF/CASPT2, CCSD(T)-F12, and DFT were used to study electronic structures and excited states of germanium trimers singly doped with titanium. All necessary parameters and calculations process are reported in the text. The conclusion on electronic transitions causing anion photoelectron bands was made by analysis of electronic structures and comparison with experimental data (reported by an experimental group).

Geometries and electronic structures of the ground and low-lying excited states of FeCO: An ab initio study

2012 ◽  
Vol 137 (24) ◽  
pp. 244303 ◽  
Author(s):  
Tsuneo Hirano ◽  
Rei Okuda ◽  
Umpei Nagashima ◽  
Per Jensen
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Electronic Structures ◽  
Ab Initio Study

scholarly journals Energetic Degeneracy and Electronic Structures of Germanium Trimers Doped with Titanium

2020 ◽  
Author(s):  
Le Nhan Pham ◽  
Salvy P. Russo
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Electronic Transitions ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Experimental Group ◽  
Comparison With Experimental Data

Several quantum chemical methods including CASSCF/CASPT2, CCSD(T)-F12, and DFT were used to study electronic structures and excited states of germanium trimers singly doped with titanium. All necessary parameters and calculations process are reported in the text. The conclusion on electronic transitions causing anion photoelectron bands was made by analysis of electronic structures and comparison with experimental data (reported by an experimental group).

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.

scholarly journals Ab Initio Study of Martensitic Transformation in NiTiPt High Temperature Shape Memory Alloys

2021 ◽  
Vol 11 (15) ◽  
pp. 6878
Author(s):  
Xiaolan Yang ◽  
Jiaxiang Shang
Keyword(s):  
Phase Transition ◽  
Martensitic Transformation ◽  
Electronic Structures ◽  
Density Functional ◽  
Martensite Phase ◽  
Computational Results ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Phase Transition Temperatures ◽  
Martensite Structure

The crystal structures and martensitic transformation of Ti50Ni50−xPtx alloys (x = 0, 6.25, 8.33, 10.42, 12.5, 18.75, 25) were studied by means of density functional theory (DFT). The computational results indicate that the lattice parameters of Ti-Ni-Pt alloys continuously increase with increasing the Pt content. It is found that at ≤ 12.5 at.% Pt, the martensite structure is monoclinic B19′ phase, and the energy differences between parent and martensite phases (ΔE) decrease slightly with a minimum observed at 6.25 at.% Pt. However, when the Pt content is increased to around 15 at.%, the most stable martensite phase is the orthorhombic B19 structure, and the ΔE increases sharply with Pt concentration. It was found that the phase transition temperatures are closely related to the energy differences ΔE between parent and martensite phases. The electronic structures of martensite B19 and B19′ phases are also discussed.

scholarly journals Electronic Structures of Purine Bases Studied by Electrochemical-ESR Techniques. Spin Distribution in Purine Anion Radical

1980 ◽  
Vol 53 (5) ◽  
pp. 1252-1256 ◽  
Author(s):  
Hiroaki Ohya-Nishiguchi ◽  
Yasunori Shimizu ◽  
Noboru Hirota ◽  
Kohji Watanabe
Keyword(s):  
Electronic Structures ◽  
Anion Radical ◽  
Spin Distribution ◽  
Purine Bases

SEMIEMPIRICAL SCF–LCAO–MO TREATMENT OF THIOPHENE, FURAN, AND PYRROLE

1965 ◽  
Vol 43 (5) ◽  
pp. 1569-1576 ◽  
Author(s):  
N. Solony ◽  
F. W. Birss ◽  
John B. Greenshields
Keyword(s):  
Experimental Data ◽  
Satisfactory Agreement ◽  
Electronic Structures ◽  
Spectroscopic Data ◽  
Variable Parameter ◽  
Coulomb Repulsion ◽  
Resonance Integral ◽  
Electronic Transitions ◽  
The Core ◽  
Lcao Mo

The semiempirical SCF–LCAO–MO method of Pariser–Parr–Pople is utilized in the study of the π-electronic structures of thiophene, furan, and pyrrole. The core Hamiltonian expansion contains a Uz++ term, the potential due to the ionized hetero-atom contributing two electrons to the π-system. The γzz, one-center coulomb repulsion integral for the hetero-atom is evaluated from the experimental spectroscopic data only. With the resonance integral βczc as the only variable parameter, the calculated π*–π electronic transitions are in a satisfactory agreement with the experimental data.

Crystal and electronic structures of superhard B2CN : An ab initio study

2012 ◽  
Vol 152 (2) ◽  
pp. 71-75 ◽  
Author(s):  
Quan Li ◽  
Dan Zhou ◽  
Hui Wang ◽  
Wanjin Chen ◽  
Baojia Wu ◽  
...  
Keyword(s):  
Ab Initio ◽  
Electronic Structures ◽  
Ab Initio Study
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