A new implementation ofab initioehrenfest dynamics using electronic configuration basis: Exact formulation with molecular orbital connection and effective propagation scheme with locally quasi-diabatic representation

2016 ◽  
Vol 116 (16) ◽  
pp. 1205-1213 ◽  
Author(s):  
Tomotaka Kunisada ◽  
Hiroshi Ushiyama ◽  
Koichi Yamashita
Keyword(s):  
Molecular Orbital ◽  
Electronic Configuration ◽  
Exact Formulation ◽  
Diabatic Representation

scholarly journals DOPANT EFFECT ON PHENALENE BANDGAP CONTROL: A HÜCKEL MOLECULAR ORBITAL PERSPECTIVE

Química Nova ◽  
2021 ◽  
Author(s):  
Muhammad Irham ◽  
Mohamad Anrokhi ◽  
Yunita Anggraini ◽  
Inge Sutjahja
Keyword(s):  
Molecular Orbital ◽  
Rotational Symmetry ◽  
Electronic Configuration ◽  
Orbital Energy ◽  
Photoluminescence Intensity ◽  
Gap Energy ◽  
Hückel Theory ◽  
Level Degeneracy ◽  
Energy Average ◽  
Good Agreement

In this study, we investigate the effects of nitrogen and boron dopants on the properties of phenalene/phenalenyl systems based on the Hückel theory by using the Hueckel Molecular Orbital software. The dopants configurations are graphitic, pyridinic, and pyrrolic. The electronic configuration of bare phenalene confirms the delocalization of π electrons and the radical properties of the molecule, which is in good agreement with the results of previous studies. Dopant types and positions strongly affect the number of π electrons in the system, molecular orbital energy, total energy, average π-electron energy, and gap energy. The molecular energy level degeneracy strongly depends on the rotational symmetry of the system, in the order of graphitic, pyridinic, and pyrrolic. A preserved radical behavior and the number of π electrons are found for the pyridinic dopant type, while closed electronic configuration is observed for graphitic and pyrrolic types. A lower gap energy is typically found for B-doped phenalene compared to that for N-doped phenalene; this opens the possibility for the enhancement of photoluminescence intensity. This study, although qualitative, confirms the effects of dopants on the chemical and physical properties of phenalene/phenalenyl systems.

scholarly journals An advanced trick to calculate the molecules and ions bond order with practical application

2021 ◽  
Author(s):  
CI Chemistry International
Keyword(s):  
Molecular Orbital ◽  
Bond Order ◽  
Electronic Configuration ◽  
Molecular Orbital Theory ◽  
Practical Application ◽  
Orbital Theory ◽  
Time Saving ◽  
New Formula ◽  
Acceptable Theory

Every molecule has two or more atoms linked to each other through a bond. The number of bonds between two atoms is called bond order. Hence, the bond order gives information about the total number of bonds between two atoms. Besides, different methods and definitions have been given to find out an exact bond order based on various theories. The most acceptable theory to find an exact bond order is the molecular orbital theory. Using this theory, the whole electronic configuration of the molecule is written first, then total electrons present in bonding orbitals as well as antibonding orbitals are counted. After that, the bond order is calculated using an old and time-consuming formula. The presented paper describes an advanced, easy, and time-saving method, named as an advanced trick/method, with a new formula to find out an exact bond order. In this trick, only total electrons and the number of antibonding electrons is considered to calculate the bond order using developed strategy with practical examples.

Interactions between Methylene Blue and Pullulan According to Molecular Orbital Calculations

2020 ◽  
Vol 140 (11) ◽  
pp. 529-533
Author(s):  
Pasika Temeepresertkij ◽  
Saranya Yenchit ◽  
Michio Iwaoka ◽  
Satoru Iwamori
Keyword(s):  
Methylene Blue ◽  
Molecular Orbital ◽  
Molecular Orbital Calculations

Parallel Fock Matrix Construction Algorithm for Molecular Orbital Calculation Specific Computer

2006 ◽  
Vol 5 (1) ◽  
pp. 179-188
Author(s):  
Hiroaki UMEDA ◽  
Yuichi INADOMI ◽  
Hiroaki HONDA ◽  
Umpei NAGASHIMA
Keyword(s):  
Molecular Orbital ◽  
Molecular Orbital Calculation ◽  
Construction Algorithm ◽  
Matrix Construction

Resolving the Quadruple Bonding Conundrum in C2 Using Insights Derived from Excited State Potential Energy Surfaces: A Molecular Orbital Perspective

2019 ◽  
Author(s):  
Ishita Bhattacharjee ◽  
Debashree Ghosh ◽  
Ankan Paul
Keyword(s):  
Excited State ◽  
Potential Energy ◽  
Molecular Orbital ◽  
High Spin ◽  
Potential Energy Surfaces ◽  
Valence Bond ◽  
Deep Minimum ◽  
State Potential ◽  
Energy Surfaces ◽  
Mo Theory

The question of quadruple bonding in C<sub>2</sub> has emerged as a hot button issue, with opinions sharply divided between the practitioners of Valence Bond (VB) and Molecular Orbital (MO) theory. Here, we have systematically studied the Potential Energy Curves (PECs) of low lying high spin sigma states of C<sub>2</sub>, N<sub>2</sub> and Be<sub>2</sub> and HC≡CH using several MO based techniques such as CASSCF, RASSCF and MRCI. The analyses of the PECs for the<sup> 2S+1</sup>Σ<sub>g/u</sub> (with 2S+1=1,3,5,7,9) states of C<sub>2</sub> and comparisons with those of relevant dimers and the respective wavefunctions were conducted. We contend that unlike in the case of N<sub>2</sub> and HC≡CH, the presence of a deep minimum in the <sup>7</sup>Σ state of C<sub>2</sub> and CN<sup>+</sup> suggest a latent quadruple bonding nature in these two dimers. Hence, we have struck a reconciliatory note between the MO and VB approaches. The evidence provided by us can be experimentally verified, thus providing the window so that the narrative can move beyond theoretical conjectures.

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

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