Positronium formation as a three-body reaction. II. The second-order nuclear amplitudes

2009 ◽  
Vol 50 (1) ◽  
pp. 013501 ◽  
Author(s):  
F. Shojaei ◽  
E. Ghanbari-Adivi ◽  
M. J. Brunger ◽  
M. A. Bolorizadeh
Keyword(s):  
Second Order ◽  
Positronium Formation ◽  
Three Body

scholarly journals Positronium formation as a three-body reaction. I. The second-order positron-electron interaction amplitude

2007 ◽  
Vol 48 (3) ◽  
pp. 033506 ◽  
Author(s):  
M. A. Bolorizadeh ◽  
M. J. Brunger ◽  
T. Maddern ◽  
E. Ghanbari Adivi
Keyword(s):  
Second Order ◽  
Positronium Formation ◽  
Electron Interaction ◽  
Interaction Amplitude ◽  
Three Body

scholarly journals First order normalization in the generalized photo gravitational non-planar restricted three body problems

2015 ◽  
Vol 3 (2) ◽  
pp. 46
Author(s):  
Nirbhay Kumar Sinha
Keyword(s):  
Oblate Spheroid ◽  
Second Order ◽  
Elliptic Motion ◽  
First Order ◽  
Short Period ◽  
Order Part ◽  
Three Body

<p>In this paper, we normalised the second-order part of the Hamiltonian of the problem. The problem is generalised in the sense that fewer massive primary is supposed to be an oblate spheroid. By photogravitational we mean that both primaries are radiating. With the help of Mathematica, H<sub>2</sub> is normalised to H<sub>2</sub> = a<sub>1</sub>b<sub>1</sub>w<sub>1</sub> + a<sub>2</sub>b<sub>2</sub>w<sub>2</sub>. The resulting motion is composed of elliptic motion with a short period (2p/w<sub>1</sub>), completed by an oscillation along the z-axis with a short period (2p/w<sub>2</sub>).</p>

Temperature Dependence of Second and Higher Order Elastic Constants of Orientationally Disordered (NH4I)x (KI)1-x Mixed Crystals

2014 ◽  
Vol 1047 ◽  
pp. 65-70 ◽  
Author(s):  
Alpana Tiwari
Keyword(s):  
Elastic Constants ◽  
Body Force ◽  
Coupling Effect ◽  
Second Order ◽  
Mixed Crystals ◽  
Elastic Behaviour ◽  
Coupling Term ◽  
Third Order ◽  
Third Order Elastic Constants ◽  
Three Body

We have incorporated the translational rotational (TR) coupling effects in the framework of three body force shell model (TSM) to develop an extended TSM (ETSM). This ETSM has been applied to reveal the second order elastic constants (C11, C12and C44) in the dilute regimes 0≤ x ≤ 0.50 as a function of temperature for 10K≤T≤300K. The anomalous elastic behaviour in C44below 100 K has been depicted well by ETSM results in the orientationally disordered (NH4I)x(KI)1-xmixed crystals. In order to present a visual comparison of the TR-coupling effect on second order elastic constants, we have evaluated the SOECs with and without TR coupling term in ETSM. Besides third order elastic constants have also been studied and discussed for concentration range 0≤x≤0.50 as a function of temperature for 10K≤T≤300K.

Second-order relativistic corrections for the S(L=0) states in one- and two-electron atomic systems

2005 ◽  
Vol 83 (1) ◽  
pp. 1-21
Author(s):  
Alexei M Frolov ◽  
Catalin C Mitelut ◽  
Zheng Zhong
Keyword(s):  
Second Order ◽  
Electron Systems ◽  
Specific Interest ◽  
Atomic Systems ◽  
Expectation Value ◽  
Relativistic Corrections ◽  
Alternative Approach ◽  
Compensation Technique ◽  
Three Body ◽  
Regular Operators

An analytical approach is developed to compute the first- (~α2) and second-order (~α4) relativistic corrections in one- and two-electron atomic systems. The approach is based on the reduction of all operators to divergent (singular) and nondivergent (regular) parts. Then, we show that all the divergent parts from the differentmatrix elements cancel each other. The remaining expression contains only regular operators and its expectation value can be easily computed. Analysis of the S(L = 0) states in such systems is of specific interest since the corresponding operators for these states contain a large number of singularities. For one-electron systems the computed relativistic corrections coincide exactly with the appropriate result that follows from the Taylor expansion of the relativistic (i.e., Dirac) energy. We also discuss an alternative approach that allows one to cancel all singularities by using the so-called operator-compensation technique. This second approach is found to be very effective in applications of more complex systems, such as helium-like atoms and ions, H+2-like ions, and some exotic three-body systems.

scholarly journals Four-body treatment of the K-shell positronium formation from multi-electron atoms

Open Physics ◽  
2014 ◽  
Vol 12 (3) ◽  
Author(s):  
Ebrahim Ghanbari-Adivi ◽  
Azime Velayati
Keyword(s):  
Cross Sections ◽  
Bound States ◽  
Transition Amplitude ◽  
Wave Functions ◽  
Positronium Formation ◽  
Distorted Wave ◽  
Helium Atoms ◽  
Three Body ◽  
Impact Energies ◽  
Correct Boundary Conditions

AbstractThe four-body Coulomb-Born distorted-wave approximation with correct boundary conditions (CBDW-4B) is applied to the K-shell positronium formation from multi-electron atoms at intermediate and high impact energies. In the present approach, both K-shell electrons are treated as active electrons. For collisions of positrons with helium, carbon, and neon atoms, both the post and prior forms of the transition amplitude are calculated and the corresponding differential and integral cross sections are compared with the results of the three-body version of the formalism (CBDW-3B). In order to investigate the effects of the static electronic correlations on the process, initial bound states of the active electrons in helium atoms are described by Hylleraas and Silverman wave functions. Also for positronium formation from helium atoms the obtained cross sections are compared with the available experimental data and also with the results of the other theories.

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