Quantum-chemical electronic-structure and electronic-spectrum calculations for tetrabenzoporphyrin N-heteroanalogs

1988 ◽  
Vol 49 (5) ◽  
pp. 1165-1171
Author(s):  
V. A. Kuz'mitskii ◽  
K. N. Solov'ev ◽  
V. N. Kopranenkov
Keyword(s):  
Electronic Structure ◽  
Electronic Spectrum ◽  
Quantum Chemical

Quantum chemical studies in the design of organic metals. III. Odd-alternant hydrocarbons - The phenalenyl (ply) system

1975 ◽  
Vol 28 (11) ◽  
pp. 2343 ◽  
Author(s):  
RC Haddon
Keyword(s):  
Electronic Structure ◽  
Structural Change ◽  
Ground State ◽  
Quantum Chemical ◽  
Low Energy ◽  
Organic Metals ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Alternant Hydrocarbons ◽  
Equilibrium Geometries

The MINDO/3 SCF MO method has been used to investigate the equilibrium geometries, electronic structure and ground state properties of ply and its univalent ions. The results indicate that ply has a low energy of disproportionation and that electron addition or removal leads to little structural change. From an analysis of the results it is concluded that odd-alternant hydrocarbons, and systems based on the ply nucleus in particular, have many of the characteristics which are considered to be important in the design of organic metals and superconductors.

Electronic structure of C60F36 studied by quantum-chemical modeling of experimental photoemission and x-ray absorption spectra

2009 ◽  
Vol 130 (1) ◽  
pp. 014704 ◽  
Author(s):  
L. G. Bulusheva ◽  
A. V. Okotrub ◽  
V. V. Shnitov ◽  
V. V. Bryzgalov ◽  
O. V. Boltalina ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Absorption Spectra ◽  
Quantum Chemical ◽  
Quantum Chemical Modeling ◽  
Chemical Modeling ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Thermodynamic Parameters of PbTe Crystals: DFT-Calculations

2015 ◽  
Vol 16 (1) ◽  
pp. 28-33
Author(s):  
D. M. Freik ◽  
B. P. Volochanska ◽  
T. O. Parashchuk
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Electronic Structure ◽  
Thermodynamic Parameters ◽  
Quantum Chemical ◽  
Density Functional ◽  
Cubic Phase ◽  
Functional Theory ◽  
Temperature Dependences ◽  
Analytical Expressions

Based on the analysis of the crystal NaCl type and electronic structure of cubic phase CdS crystals the cluster models have been built for calculation of the geometric and thermodynamic parameters. According to density functional theory (DFT) and using the hybrid valence base set B3LYP the temperature dependence of the energy ΔE and the enthalpy ΔH of formation, Gibbs free energy ΔG, entropy ΔS, specific heat at constant volume CV and pressure CP of the crystals have been found. The analytical expressions of the temperature dependences of presented thermodynamic parameters which was approximated from the quantum- chemical calculations data and with using mathematical package Maple 14 have been received.

scholarly journals Determining Partial Atomic Charges for Liquid Water: Assessing Electronic Structure and Charge Models

2020 ◽  
Author(s):  
Bowen Han ◽  
Christine Isborn ◽  
Liang Shi
Keyword(s):  
Electronic Structure ◽  
Dipole Moment ◽  
Charge Transfer ◽  
Liquid Water ◽  
Quantum Chemical ◽  
Water Dimer ◽  
Atomic Charges ◽  
Molecular Dipole ◽  
Molecular Dipole Moment ◽  
Partial Atomic Charges

Partial atomic charges provide an intuitive and efficient way to describe the charge distribution and the resulting intermolecular electrostatic interactions in liquid water. Many charge models exist and it is unclear which model provides the best assignment of partial atomic charges in response to the local molecular environment. In this work, we systematically scrutinize various electronic structure methods and charge models (Mulliken, Natural Population Analysis, CHelpG, RESP, Hirshfeld, Iterative Hirshfeld, and Bader) by evaluating their performance in predicting the dipole moments of isolated water, water clusters, and liquid water as well as charge transfer in the water dimer and liquid water. Although none of the seven charge models is capable of fully capturing the dipole moment increase from isolated water (1.85 D) to liquid water (about 2.9 D), the Iterative Hirshfeld method performs best for liquid water, reproducing its experimental average molecular dipole moment, yielding a reasonable amount of intermolecular charge transfer, and showing modest sensitivity to the local water environment. The performance of the charge model is dependent on the choice of the density functional and the quantum treatment of the environment. The computed molecular dipole moment of water generally increases with the percentage of the exact Hartree-Fock exchange in the functional, whereas the amount of charge transfer between molecules decreases. For liquid water, including two full solvation shells of surrounding water molecules (within about 5.5 A of the central water) in the quantum-chemical calculation converges the charges of the central water molecule. Our final pragmatic quantum-chemical charge assigning protocol for liquid water is the Iterative Hirshfeld method with M06-HF/aug-cc-pVDZ and a quantum region cutoff radius of 5.5 A.<br>

Electronic structure of Zn-chlorin π-anions studied by spectroscopic and quantum-chemical methods

1995 ◽  
Vol 1 (3) ◽  
pp. 223-234 ◽  
Author(s):  
A. M. Shulga ◽  
G. N. Sinyakov ◽  
I. V. Filatov ◽  
G. P. Gurinovich ◽  
K. Dzilinski
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical ◽  
Chemical Methods ◽  
Quantum Chemical Methods

scholarly journals Conformational behavior and electronic structure of silylketenes studied with quantum chemical calculations and photoelectron spectroscopy

1997 ◽  
Vol 75 (12) ◽  
pp. 1851-1861 ◽  
Author(s):  
Heidi M. Muchall ◽  
Nick H. Werstiuk ◽  
Jiangong Ma ◽  
Thomas T. Tidwell ◽  
Kuangsen Sung
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical Calculations ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Computational Study ◽  
Photoelectron Spectra ◽  
Conformational Behavior ◽  
Torsional Angle ◽  
Orbital Interaction ◽  
Orbital Energies

The He(I) photoelectron spectra of silylketenes (Me3Si)2C=C=O (1), Me5Si2CH=C=O (2), Me2Si(CH=C=O)2 (3), MeSi(CH=C=O)3 (4), (SiMe2CH=C=O)2 (5), and (CH2SiMe2CH=C=O)2 (6) have been recorded and their structures and orbital energies have been calculated by ab initio methods. Orbital energies for disilanes 2 and 5 are strongly dependent on a Si-Si-C-C torsional angle due to σ–π orbital interaction. Comparisons between experimental and simulated spectra show that 2 and 5 prefer conformations in which the Si—Si bond and ketene group(s) are approximately orthogonal (113° and 111°, respectively). Silylalkenes Me5Si2CH=CH2 (7) and (SiMe2CH=CH2)2 (8), which have been included in the computational study, show the same behavior as their corresponding silylketenes. Silylbis- and trisketenes 3–6 do not exhibit π–π interaction of any significance. For Si—Si containing compounds, the best agreement between experimental and computed data was obtained when Becke3LYP/6-31G*//HF/3-21G* was employed. Keywords: conformational behavior, electronic structure, photoelectron spectroscopy, quantum chemical calculations, silylketenes.

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