An experimental and theoretical study of the momentum distribution of two photon annihilating positron–electron pairs in methane

1968 ◽  
Vol 46 (20) ◽  
pp. 2309-2313 ◽  
Author(s):  
S. Y. Chuang ◽  
W. H. Holt ◽  
B. G. Hogg

The momentum distributions of annihilating positron–electron pairs have been measured in liquid and solid methane. Calculated momentum distributions generally assume that the positron wave function ψ+ = 1. This low-momentum, plane-wave representation of the positron is inadequate to describe the experimental distribution for high momenta. A ψ+ obtained by numerical integration of the ground-state radial Schrödinger equation is employed in the calculation and a good fit is observed with experiment for all momentum values.

1967 ◽  
Vol 45 (12) ◽  
pp. 3895-3900 ◽  
Author(s):  
S. Y. Chuang ◽  
B. G. Hogg

Momentum distributions are calculated for electrons in the C–C and C–H bonds in hydrocarbons, using analytic SCF functions for atomic carbon orbitals and Heitler–London-type functions for the two paired electrons in the C–C and C–H bonds. The positron wave function is assumed to be a constant. The computed momentum distributions are then compared with high-precision experimental distributions obtained from positron-annihilation angular correlation experiments.


1972 ◽  
Vol 50 (15) ◽  
pp. 1777-1781 ◽  
Author(s):  
S. M. Kim ◽  
W. J. L. Buyers

Measurements have been made of the two-photon angular correlation from positrons annihilating in single-crystal molybdenum at room temperature. By means of a combination of conventional slits and Soller slits the number of annihilations for which the momentum lies along a line in the momentum distribution is obtained, and results are presented for the [ζ,ζ,0], [0,0,ζ, and [ζ,ζ,0.71] directions. Theoretical calculations of the angular correlation have been made based on the interpolation or pseudopotential scheme with s–d interaction included. The parameters of the interpolation scheme have been chosen so that an accurate representation is obtained of the APW band structure of Mattheiss. The positron wave function has been obtained in terms of 141 plane waves. The width of the calculated two-photon angular correlation is found to be much broader than the experimental width unless the relative s and d enhancement is considered.


2018 ◽  
Vol 2 (2) ◽  
pp. 43-47
Author(s):  
A. Suparmi, C. Cari, Ina Nurhidayati

Abstrak – Persamaan Schrödinger adalah salah satu topik penelitian yang yang paling sering diteliti dalam mekanika kuantum. Pada jurnal ini persamaan Schrödinger berbasis panjang minimal diaplikasikan untuk potensial Coulomb Termodifikasi. Fungsi gelombang dan spektrum energi yang dihasilkan menunjukkan kharakteristik atau tingkah laku dari partikel sub atom. Dengan menggunakan metode pendekatan hipergeometri, diperoleh solusi analitis untuk bagian radial persamaan Schrödinger berbasis panjang minimal diaplikasikan untuk potensial Coulomb Termodifikasi. Hasil yang diperoleh menunjukkan terjadi peningkatan energi yang sebanding dengan meningkatnya parameter panjang minimal dan parameter potensial Coulomb Termodifikasi. Kata kunci: persamaan Schrödinger, panjang minimal, fungsi gelombang, energi, potensial Coulomb Termodifikasi Abstract – The Schrödinger equation is the most popular topic research at quantum mechanics. The  Schrödinger equation based on the concept of minimal length formalism has been obtained for modified Coulomb potential. The wave function and energy spectra were used to describe the characteristic of sub-atomic particle. By using hypergeometry method, we obtained the approximate analytical solutions of the radial Schrödinger equation based on the concept of minimal length formalism for the modified Coulomb potential. The wave function and energy spectra was solved. The result showed that the value of energy increased by the increasing both of minimal length parameter and the potential parameter. Key words: Schrödinger equation, minimal length formalism (MLF), wave function, energy spectra, Modified Coulomb potential


2007 ◽  
Vol 21 (24) ◽  
pp. 1635-1642
Author(s):  
MIAN LIU ◽  
WENDONG MA ◽  
ZIJUN LI

We conducted a theoretical study on the properties of a polaron with electron-LO phonon strong-coupling in a cylindrical quantum dot under an electric field using linear combination operator and unitary transformation methods. The changing relations between the ground state energy of the polaron in the quantum dot and the electric field intensity, restricted intensity, and cylindrical height were derived. The numerical results show that the polar of the quantum dot is enlarged with increasing restricted intensity and decreasing cylindrical height, and with cylindrical height at 0 ~ 5 nm , the polar of the quantum dot is strongest. The ground state energy decreases with increasing electric field intensity, and at the moment of just adding electric field, quantum polarization is strongest.


Author(s):  
S. Gallego-Parra ◽  
R. Vilaplana ◽  
O. Gomis ◽  
E. Lora da Silva ◽  
A. Otero-de-la-Roza ◽  
...  

We report a joint experimental and theoretical study of the low-pressure phase of α′-Ga2S3 under compression. The structural, vibrational, topological and electronic properties have been evaluated to reveal the relevance of the vacancy channels and the single and double lone electron pairs in the pressure behaviour of this system.


2021 ◽  
Vol 103 (12) ◽  
Author(s):  
Jintae Kim ◽  
Minsoo Kim ◽  
Pramod Padmanabhan ◽  
Jung Hoon Han ◽  
Hyun-Yong Lee

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