scholarly journals Polarons on Dimerized Lattice of Polyacetilene. Continuum Approximation

2021 ◽  
Vol 16 (2) ◽  
pp. 335-348
Author(s):  
T.Yu. Astakhova ◽  
G.A. Vinogradov
Keyword(s):  
Numerical Simulation ◽  
Analytical Solution ◽  
Electric Field ◽  
Valence Band ◽  
Continuum Approximation ◽  
Electron Model ◽  
Speed Range ◽  
Freely Moving ◽  
The Many

A one-electron model is proposed to describe a polaron on a dimerized polyacetylene lattice. Within the framework of the formulated model, the dynamics of a freely moving polaron is considered. The results obtained are compared with the many-electron model that takes into account all π-electrons of the valence band. Polaron can move at subsonic and supersonic speeds. The subsonic polaron is stable. A supersonic polaron loses stability at times ∼ 6 000 fs. A supersonic polaron has a forbidden speed range. An analytical solution to the continual approximation helps to understand the reason for the existence of forbidden speeds. The dynamics of a free polaron is similar to the dynamics of a polaron in an electric field. The proposed one-electron approximation significantly expands the possibilities of numerical simulation in comparison with the traditional many-electron model.

Numerical Simulation of Leakage Current on Conductive Insulator Surface

2019 ◽  
Vol 8 (4) ◽  
pp. 9487-9492
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Leakage Current ◽  
Method Of Lines ◽  
Electron Attachment ◽  
Negative Ions ◽  
Conduction Current ◽  
Insulator Surface ◽  
Finite Difference Approximations ◽  
Positive Ions

The outdoor insulator is commonly exposed to environmental pollution. The presence of water like raindrops and dew on the contaminant surface can lead to surface degradation due to leakage current. However, the physical process of this phenomenon is not well understood. Hence, in this study we develop a mathematical model of leakage current on the outdoor insulator surface using the Nernst Planck theory which accounts for the charge transport between the electrodes (negative and positive electrode) and charge generation mechanism. Meanwhile the electric field obeys Poisson’s equation. Method of Lines technique is used to solve the model numerically in which it converts the PDE into a system of ODEs by Finite Difference Approximations. The numerical simulation compares reasonably well with the experimental conduction current. The findings from the simulation shows that the conduction current is affected by the electric field distribution and charge concentration. The rise of the conduction current is due to the distribution of positive ion while the dominancy of electron attachment with neutral molecule and recombination with positive ions has caused a significant reduction of electron and increment of negative ions.

Coupled-pair theories and Davidson-type corrections for quasidegenerate states: The H4 model revisited

1988 ◽  
Vol 53 (9) ◽  
pp. 1919-1942 ◽  
Author(s):  
Josef Paldus ◽  
Paul E. S. Wormer ◽  
Marc Benard
Keyword(s):  
Electron Correlation ◽  
Model System ◽  
Coupled Cluster ◽  
Electron Model ◽  
Hydrogen Molecules ◽  
Double Zeta ◽  
Correlation Problem ◽  
Variational Approaches ◽  
Cluster Type ◽  
The Many

The performance of various variational and non-variational approaches to the many-electron correlation problem is examined for a simple four-electron model system consisting of two stretched hydrogen molecules in trapezoidal, rectangular and linear configurations, in which the degree of quasi-degeneracy can be continuously varied from a non-degenerate to an almost degenerate situation. In contrast to an earlier work (K. Jankowski and J. Paldus, Int. J. Quantum Chem. 18, 1243 (1980)) we employ a double-zeta plus polarization basis and examine both single reference and multireference configuration interaction and coupled-cluster-type approaches. The performance of various Davidson-type corrections is also investigated.

Experimental Investigation and Numerical Simulation of Porous Volcano Rock Hypervelocity Impact on Whipple Shield of Spacecrafts

2010 ◽  
Vol 452-453 ◽  
pp. 385-388
Author(s):  
Bin Jia ◽  
Gao Jian Liao ◽  
Hai Peng Gong ◽  
Bao Jun Pang
Keyword(s):  
Numerical Simulation ◽  
Space Debris ◽  
Geometrical Model ◽  
Hypervelocity Impact ◽  
Rear Wall ◽  
Projectile Impact ◽  
Gas Gun ◽  
Significant Damage ◽  
Speed Range ◽  
Whipple Shield

All spacecrafts in earth orbit are subject to hypervelocity impact by micro-meteoroids and space debris, which can in turn lead to significant damage and catastrophic failure of spacecraft. Porous volcano rock was adopted as one of micro-meteoroid material due to their similar physical and geometric features. Two-stage light gas gun experiments were carried out for a 6mm diameter volcano rock projectile impact on an Al-Whipple shield within the speed range from 1 km/s to 3 km/s. An ANSYS/LS-DYNA software was employed and justified by experimental results, in which a porous geometrical model was established for volcano rock projectile. The higher speed range was extended from 3 km/s to 10 km/s by numerical simulation. The results of experiments and numerical simulation indicated that major damage on rear wall of the Whipple shield impacted by volcano rock projectile is caused by the fragments of bumper of the shield, which is different from that of aluminum projectile. And 5.5km/s is the critical speed of a 6mm diameter volcano rock projectile impact on the Whipple shield investigated.

Numerical Simulation of Influence of Baffler in Electric Field Entrance to Form Skewed Gas Flow

2009 ◽  
pp. 187-193
Author(s):  
Hu Manyin ◽  
Sun Xijuan ◽  
Ma Chunhong ◽  
Liu Yujing ◽  
Wang Li-qian
Keyword(s):  
Numerical Simulation ◽  
Electric Field ◽  
Gas Flow
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