Molecular orbital perturbation theory II. Charge displacement and stabilization in conjugated molecules

1955 ◽  
Vol 233 (1193) ◽  
pp. 241-247 ◽  
Keyword(s):  
Perturbation Theory ◽  
Charge Distribution ◽  
Lone Pair ◽  
Electron Interaction ◽  
Electron Model ◽  
Conjugated Molecules ◽  
Orbital Perturbation ◽  
Self Consistent ◽  
Charge Displacement ◽  
Lone Pair Electrons

The general perturbation method outlined in part I is used to study energy and charge distribution changes caused by inductive and electromeric-type perturbations in conjugated molecules. Self-consistent orbitals for the unperturbed systems are found by approximating electron interaction integrals and are used as a basis for the perturbed systems. It is found that the change of charge distribution caused by an inductive substituent in benzene is similar to that predicted by the independent-electron model. Second-order perturbation theory is used to discuss electromeric displacements in which lone pair electrons take part in conjugation.

Molecular orbital perturbation theory II. Charge displacement and stabilization in conjugated molecules

1955 ◽  
Vol 233 (1193) ◽  
pp. 233-241 ◽  
Keyword(s):  
Wave Function ◽  
Molecular Orbital ◽  
Excited States ◽  
Electron Interaction ◽  
Unperturbed System ◽  
Electron Model ◽  
Conjugated Molecules ◽  
Orbital Perturbation ◽  
Self Consistent ◽  
Charge Displacement

This paper develops a method of investigating changes in the electronic structure of a molecule caused by a perturbation such as a substituent or the field of another particle. The method is based on a Hamiltonian including electron interaction. The total wave function for the perturbed molecule is written as a linear combination of approximate self-consistent molecular orbital functions for the ground and excited states of the unperturbed system . First- and second-order expressions for changes in energy and charge distribution are given which are generalizations of results previously obtained using an independent-electron model.

Pertubation Theory About Self-Consistent Field Solution in One-Dimensional Hubbard Model

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3363-3366 ◽  
Author(s):  
A. N. Kocharian ◽  
C. Yang ◽  
Y. L. Chiang
Keyword(s):  
Perturbation Theory ◽  
Hubbard Model ◽  
Electron Concentration ◽  
Ground State ◽  
Second Order ◽  
Electron Interaction ◽  
Field Solution ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field

The accurate analytical and numerical calculations of the electronic band structure and ground state properties of strongly correlated electrons within the Hubbard model are performed by constructing convergent perturbation theory for general interaction strength and electron concentration. We test the developed perturbation approach about mean field solution in the extreme conditions of one dimensionality for entire parameter space of electron interaction U/t and electron concentration n. The many-body perturbation formalism up two second order about the generalized self-consistent field (GSCF) Hamiltonian goes beyond the range of applicability of standard perturbation theory by incorporating systematically the effect of the random-phase-type perturbation techniques and controlled expansion of the energy functional for general U/t and n. The second order perturbation correction vanishes at small and large U/t limit and performed calculations of the ground state energy show a next to the perfect numerical agreement with the Bethe-ansatz results.

Effect of delocalization of nonbonding electron density on the stability of the M–Ccarbene bond in main group metal-imidazol-2-ylidene complexes: a computational and structural database study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Samuel Tetteh ◽  
Albert Ofori
Keyword(s):  
Electron Density ◽  
Lone Pair ◽  
Main Group ◽  
Binding Energies ◽  
Electrostatic Model ◽  
Group Metal ◽  
Main Group Metal ◽  
Structural Database ◽  
The Stability ◽  
Lone Pair Electrons

Abstract The M–Ccarbene bond in metal (M) complexes involving the imidazol-2-ylidene (Im) ligand has largely been described using the σ-donor only model with donation of σ electrons from the sp-hybridized orbital of the carbene carbon into vacant orbitals on the metal centre. Analyses of the M–Ccarbene bond in a series of group IA, IIA and IIIA main group metal complexes show that the M-Im interactions are mostly electrostatic with the M–Ccarbene bond distances greater than the sum of the respective covalent radii. Estimation of the binding energies of a series of metal hydride/fluoride/chloride imidazol-2-ylidene complexes revealed that the stability of the M–Ccarbene bond in these complexes is not always commensurate with the σ-only electrostatic model. Further natural bond orbital (NBO) analyses at the DFT/B3LYP level of theory revealed substantial covalency in the M–Ccarbene bond with minor delocalization of electron density from the lone pair electrons on the halide ligands into antibonding molecular orbitals on the Im ligand. Calculation of the thermodynamic stability of the M–Ccarbene bond showed that these interactions are mostly endothermic in the gas phase with reduced entropies giving an overall ΔG > 0.

scholarly journals Long-term stability in γ-CsPbI3 perovskite via an ultraviolet-curable polymer network

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Nam-Kwang Cho ◽  
Hyun-Jae Na ◽  
Jeeyoung Yoo ◽  
Youn Sang Kim
Keyword(s):  
Polymer Network ◽  
Lone Pair ◽  
Ambient Conditions ◽  
Absorption Properties ◽  
Term Stability ◽  
Long Term Stability ◽  
Ultraviolet Curable ◽  
Oxygen Lone Pair ◽  
Lone Pair Electrons

AbstractBlack-colored (α, γ-phase) CsPbI3 perovskites have a small bandgap and excellent absorption properties in the visible light regime, making them attractive for solar cells. However, their long-term stability in ambient conditions is limited. Here, we demonstrate a strategy to improve structural and electrical long-term stability in γ-CsPbI3 by the use of an ultraviolet-curable polyethylene glycol dimethacrylate (PEGDMA) polymer network. Oxygen lone pair electrons from the PEGDMA are found to capture Cs+ and Pb2+ cations, improving crystal growth of γ-CsPbI3 around PEGDMA. In addition, the PEGDMA polymer network strongly contributes to maintaining the black phase of γ-CsPbI3 for more than 35 days in air, and an optimized perovskite film retained ~90% of its initial electrical properties under red, green, and blue light irradiation.

Sign in / Sign up

Export Citation Format

Share Document