A Valence-Bond Study of the Role of 3d Orbitals in the Bonding in ClF3

1988 ◽  
Vol 41 (4) ◽  
pp. 527 ◽  
Author(s):  
n Maclaga
Keyword(s):  
Significant Contribution ◽  
Valence Bond ◽  
Basis Set ◽  
Minimal Basis ◽  
Covalent Bonds ◽  
Calculated Energy ◽  
Covalent Structure ◽  
Important Structure

Minimal basis set valence-bond calculations on ClF3, with, and without, the use of chlorine 3d orbitals are described. The most important structure is a spin-paired diradical structure. The covalent structure with three covalent Cl -F covalent bonds has a sufficiently low importance that 3d orbitals are not essential for describing the bonding in ClF3. Chlorine 3d orbitals do have a significant contribution to the calculated energy.

Valence-bond studies on SiH3

1984 ◽  
Vol 37 (11) ◽  
pp. 2159 ◽  
Author(s):  
R Jans ◽  
RGAR Maclagan
Keyword(s):  
Silicon Atom ◽  
Negative Charge ◽  
Positive Charge ◽  
Valence Bond ◽  
Basis Set ◽  
Planar Structure ◽  
Pyramidal Structure ◽  
Double Zeta ◽  
Covalent Structure ◽  
Important Structure

Valence-bond calculations are reported for the ground state of SiH3, a contracted double-zeta basis set being used. Without the use of silicon 3d orbitals, a planar structure is predicted, but the inclusion of 3d orbitals in the basis set leads to a pyramidal structure being predicted. The covalent structure is the most important structure. Structures in which the silicon atom carries a positive charge favour a pyramidal structure, but those in which the silicon atom carries a negative charge tend to favour a planar structure.

d Orbitals in the noble-gas dihalides

1970 ◽  
Vol 48 (17) ◽  
pp. 2695-2701 ◽  
Author(s):  
R. C. Catton ◽  
K. A. R. Mitchell
Keyword(s):  
Noble Gas ◽  
Valence Bond ◽  
Ionic Character ◽  
Orbital Exponent ◽  
Covalent Bonds ◽  
Model Calculations ◽  
Pair Bonds ◽  
Electron Repulsion Integrals ◽  
D Orbitals

Model calculations are reported for ArF2, KrF2, XeF2, ArCl2, KrCl2, and XeCl2. The approach is to compare the energies of a number of valence-bond structures for each molecule. The calculations use Slater-type radial functions and simplify the electron repulsion integrals with the Mulliken approximation. Energies are optimized by varying the d orbital exponent and a parameter which governs the ionic character of the covalent bonds. For all the molecules it is found that the structures such as (X—M+X− + X−M+—X) and X−M2+X−, which maintain the octet rule and exclude the use of d orbitals, are less stable than the structure X—M—X which implies localized electron-pair bonds based on pd hybrids at the noble-gas atom M.Approximate molecular wave functions are obtained from a configuration interaction calculation, and the general conclusion is that the valence-bond structures incorporating d orbitals become more important as the atomic number of the central atom increases. A preliminary study of the role of the [Formula: see text] orbital is also presented, but it seems this orbital contributes mainly as a polarization effect.

1. Matter from the inside

2014 ◽  
pp. 1-21
Author(s):  
Peter Atkins
Keyword(s):  
Quantum Mechanics ◽  
General Structure ◽  
Valence Bond ◽  
Pauli Exclusion Principle ◽  
Exclusion Principle ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Covalent Bonds ◽  
Bond Theory

‘Matter from the inside’ shows that one way to understand how a physical chemist thinks and contributes to chemistry is to start at the atom's interior and then travel out into the world of bulk matter. It begins with the electronic structure of atoms, introduces the role of quantum mechanics in accounting for electron arrangement, and outlines Schrödinger's model of s-, p-, d-, and f-orbitals and the Pauli exclusion principle. Physical chemistry accounts for the general structure of the Periodic Table. The radius, ionization energy, and electron affinity properties of atoms are then considered along with ionic and covalent bonds, and the quantum mechanics of bonds, including valence-bond theory and molecular orbital theory.

Economic Development of Bangladesh: The Role of IBBL

IIUC Studies ◽  
2015 ◽  
Vol 9 ◽  
pp. 323-334
Author(s):  
Shafiqur Rahman ◽  
Nicholas McDonald
Keyword(s):  
Economic Development ◽  
Content Analysis ◽  
Foreign Trade ◽  
Rural Economy ◽  
Significant Contribution ◽  
Annual Report ◽  
Housing Sector

This paper presents the role of Islami Bank Bangladesh Limited (IBBL) to the recent economic development in Bangladesh. The study analyses published texts, articles, websites and annual report of this bank through a content analysis. Key findings of this study manifest the contribution of this bank in different areas of economic development in Bangladesh like generating employment, earning foreign remittance, strengthening rural economy, promoting ecology and green banking, boosting industrialization, developing the SMEs, assisting in foreign trade (import-export), developing the housing sector etc. This study also identifies IBBL’s significant contribution to the national exchequer. This paper contributes to the field of economic development of Bangladesh and the role of IBBL behind it and fills the gap of literature in this specific area.IIUC Studies Vol.9 December 2012: 323-334

Participation of ABCA1 transporter in development of chronic obstructive pulmonary disease

2020 ◽  
Vol 28 (3) ◽  
pp. 360-370
Author(s):  
Stanislav N. Kotlyarov ◽  
Anna A. Kotlyarova
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Significant Contribution ◽  
Modern Medicine ◽  
Lipid Homeostasis ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Reverse Transport ◽  
Current Paradigm

Despite all achievements of the modern medicine, the problem of chronic obstructive pulmonary disease (COPD) does not lose its relevance. The current paradigm suggests a key role of macrophages in inflammation in COPD. Macrophages are known to be heterogeneous in their functions. This heterogeneity is determined by their immunometabolic profile and also by peculiarities of lipid homeostasis of cells. Aim. To analyze the role of the ABCA1 transporter, a member of the ABC A subfamily, in the pathogenesis of COPD. The expression of ABCA1 in lung tissues is on the second place after the liver, which shows the important role of the carrier and of lipid homeostasis in the function of lungs. Analysis of the literature shows that participation of the transporter in inflammation consists in regulation of the content of cholesterol in the lipid rafts of the membranes, in phagocytosis and apoptosis. Conclusion. Through regulation of the process of reverse transport of cholesterol in macrophages of lungs, ABCA1 can change their inflammatory response, which makes a significant contribution to the pathogenesis of COPD.

scholarly journals An Investigation into the Approximations Used in Wave Packet Molecular Dynamics for the Study of Warm Dense Matter

Plasma ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 294-308
Author(s):  
William A. Angermeier ◽  
Thomas G. White
Keyword(s):  
Molecular Dynamics ◽  
Wave Packet ◽  
Hydrogen Plasma ◽  
Valence Bond ◽  
Dense Matter ◽  
Basis Set ◽  
Warm Dense Matter ◽  
Scaling Parameters ◽  
Oppenheimer Approximation ◽  
Semi Empirical

Wave packet molecular dynamics (WPMD) has recently received a lot of attention as a computationally fast tool with which to study dynamical processes in warm dense matter beyond the Born–Oppenheimer approximation. These techniques, typically, employ many approximations to achieve computational efficiency while implementing semi-empirical scaling parameters to retain accuracy. We investigated three of the main approximations ubiquitous to WPMD: a restricted basis set, approximations to exchange, and the lack of correlation. We examined each of these approximations in regard to atomic and molecular hydrogen in addition to a dense hydrogen plasma. We found that the biggest improvement to WPMD comes from combining a two-Gaussian basis with a semi-empirical correction based on the valence-bond wave function. A single parameter scales this correction to match experimental pressures of dense hydrogen. Ultimately, we found that semi-empirical scaling parameters are necessary to correct for the main approximations in WPMD. However, reducing the scaling parameters for more ab-initio terms gives more accurate results and displays the underlying physics more readily.

scholarly journals Pentagon functions for scattering of five massless particles

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
D. Chicherin ◽  
V. Sotnikov
Keyword(s):  
Phase Space ◽  
Numerical Evaluation ◽  
Public Library ◽  
Basis Set ◽  
Particle Scattering ◽  
Minimal Basis ◽  
Feynman Integrals ◽  
Analytic Expressions ◽  
Transcendental Functions ◽  
Branch Cuts

Abstract We complete the analytic calculation of the full set of two-loop Feynman integrals required for computation of massless five-particle scattering amplitudes. We employ the method of canonical differential equations to construct a minimal basis set of transcendental functions, pentagon functions, which is sufficient to express all planar and nonplanar massless five-point two-loop Feynman integrals in the whole physical phase space. We find analytic expressions for pentagon functions which are manifestly free of unphysical branch cuts. We present a public library for numerical evaluation of pentagon functions suitable for immediate phenomenological applications.

Tackling Rape Culture in Québec Universities: A Network of Feminist Resistance

2019 ◽  
Vol 25 (11) ◽  
pp. 1290-1308 ◽  
Author(s):  
Sandrine Ricci ◽  
Manon Bergeron
Keyword(s):  
Sexual Violence ◽  
Significant Contribution ◽  
Political Agenda ◽  
The Political ◽  
Feminist Activism ◽  
University Campuses ◽  
Government Institutions ◽  
University Communities ◽  
Dual Perspective

Québec university communities are facing intensified pressure to address the incidence of sexual violence on campus. The ESSIMU ( Enquête Sexualité, Sécurité et Interactions en Milieu Universitaire) survey (2016) revealed that one third of respondents (students and employees from six universities, all genders combined) reported having experienced at least one form of sexual violence since arriving at university, committed by someone affiliated with the same university. As the issue is becoming increasingly institutionalized, a process that often erodes activism, this article highlights the role feminist activism has played in placing sexual violence on university campuses on the political agenda. From the dual perspective of feminist activists and researchers on the ESSIMU team, the article explores the backdrop of this mobilization, and the network of feminist resistance that fostered the ESSIMU study, itself a significant contribution to the increased recognition of sexual violence in universities. It also considers the role of university and government institutions in (re)producing such violence and the role of media in making it a public issue.

TRANSFORMATION OF THE INTERNAL AUDIT IS AN EFFECTIVE WAY TO INCREASE THE CONTRIBUTION TO THE SUSTAINABLE DEVELOPMENT OF A BUSINESS ENTITY

2021 ◽  
Vol 2 (2) ◽  
pp. 114-119
Author(s):  
PHAN THI THANH QUYEN ◽  
Keyword(s):  
Sustainable Development ◽  
Business Model ◽  
Significant Contribution ◽  
Internal Audit ◽  
Governance Structure ◽  
Sustainable Business ◽  
Corporate Governance Structure ◽  
The Sustainable Development ◽  
Internal Auditors

The role of internal audit in ensuring sustainable development of economic entities is indisputable. How-ever, the biggest challenge faced by internal auditors is how the level of their contribution can truly be weighed against the ability and role recognized by society, especially as most economic actors move from a traditional business model to a sustainable business model. The article highlights the main approaches to the transfor-mation of internal audit in order to make it an integral part of the corporate governance structure and make a significant contribution to sustainable development.

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