scholarly journals Spherical-harmonics expansion method for density-matrix simulations of quantum electron dynamics in continuum states

2015 ◽  
Vol 115 (22) ◽  
pp. 1587-1596 ◽  
Author(s):  
Hikaru Kitamura
Keyword(s):  
Density Matrix ◽  
Spherical Harmonics ◽  
Expansion Method ◽  
Electron Dynamics ◽  
Continuum States ◽  
Quantum Electron ◽  
Spherical Harmonics Expansion

scholarly journals A review of recent advances in the spherical harmonics expansion method for semiconductor device simulation

2016 ◽  
Vol 15 (3) ◽  
pp. 939-958 ◽  
Author(s):  
K. Rupp ◽  
C. Jungemann ◽  
S.-M. Hong ◽  
M. Bina ◽  
T. Grasser ◽  
...  
Keyword(s):  
Spherical Harmonics ◽  
Semiconductor Device ◽  
Device Simulation ◽  
Expansion Method ◽  
Semiconductor Device Simulation ◽  
Recent Advances ◽  
Spherical Harmonics Expansion

Simulating the diffraction line profile from nanocrystalline powders using a spherical harmonics expansion

2018 ◽  
Vol 74 (6) ◽  
pp. 640-646
Author(s):  
K. R. Beyerlein ◽  
P. Scardi
Keyword(s):  
Line Profile ◽  
Spherical Harmonics ◽  
Diffraction Line ◽  
Nanocrystalline Powders ◽  
Computationally Efficient ◽  
Profile Function ◽  
Diffraction Line Profile ◽  
Cubic Crystallites ◽  
Crystallite Shape ◽  
Spherical Harmonics Expansion

An accurate description of the diffraction line profile from nanocrystalline powders can be obtained by a spherical harmonics expansion of the profile function. The procedure outlined in this work is found to be computationally efficient and applicable to the line profile for any crystallite shape and size. Practical examples of the diffraction pattern peak profiles resulting from cubic crystallites between 1 and 100 nm in size are shown.

scholarly journals Theoretical framework for classification and prediction of ultrafast and strong-field phenomena in solids

2019 ◽  
Vol 205 ◽  
pp. 04013
Author(s):  
Stanislav Yu. Kruchinin ◽  
Ferenc Krausz ◽  
Vladislav S. Yakovlev
Keyword(s):  
Density Matrix ◽  
Time Scales ◽  
Strong Field ◽  
Laser Pulses ◽  
Theoretical Framework ◽  
Ultrashort Laser Pulses ◽  
Matrix Equations ◽  
Electron Dynamics ◽  
Characteristic Energy ◽  
Ultrashort Laser

We study the characteristic energy and time scales describing the coherent electron dynamics and decoherence phenomena in solids interacting with ultrashort laser pulses. Our analysis resulted in the derivation system of dimensionless adiabaticity parameters and derivation of the non-Markovian density-matrix equations applicable on arbitrary short timescales.

scholarly journals Total Electron Content (TEC) estimation over Pakistan from local GPS network using spherical harmonics

2021 ◽  
Vol 64 (1) ◽  
Author(s):  
Maria Mehmood ◽  
Sajid Saleem ◽  
Renato Filjar ◽  
Najam Naqvi ◽  
Arslan Ahmed
Keyword(s):  
Spherical Harmonics ◽  
Orbit Determination ◽  
Region Of Interest ◽  
Local Model ◽  
Small Scale ◽  
Electron Content ◽  
Total Electron ◽  
Gps Network ◽  
Spherical Harmonics Expansion ◽  
The Impact

Many organizations allow GNSS users to access Global Ionosphere Maps (GIMS). However, the TEC estimates derived from GIMs are of insufficient quality to describe small-scale TEC variations over Pakistan. In this paper, the first local TEC map over Pakistan for the year 2019, derived from a regional GPS network, is presented. Spherical harmonics expansion is employed to estimate TEC with the spatial resolution of latitude 0.2° x longitude 0.2° and temporal resolution of 5 minutes. The impact of changing the degree/order of harmonics is assessed and it is determined that harmonic expansion up to 6 degrees is sufficient for estimating accurate TEC map for the region of interest. We have demonstrated that the TEC maps of Pakistan generated by local model conform better to the GIM by Center of Orbit Determination (CODE) (RMS = 5.83) as compared to International Reference Ionosphere (IRI-2016) (RMS = 7.18). We found that the TEC estimated by the local model shows a better correlation to measured TEC; CODE-GIM overestimated TEC, while IRI-2016 underestimates it. Moreover, it was observed that TEC peaks during noon (1100-0100 LT) and Equinox (April). The residuals of local TEC estimates with respect to TEC obtained from CODE- GIM indicate the inaccuracy of CODE-GIM over the region of Pakistan: highest deviation of TEC from local model with respect to CODE –GIM was observed in April (RMS = 8.73) and minimum in October (RMS = 2.78). We have also analyzed the performance of our maps in geomagnetically disturbed days. The research presented in this paper will contribute towards the ionosphere study over Pakistan, where limited research is available currently.

FISSION DYNAMICS IN THE FOUR-DIMENSIONAL DEFORMATION SPACE

2006 ◽  
Vol 15 (02) ◽  
pp. 417-425 ◽  
Author(s):  
KRZYSZTOF POMORSKI ◽  
JOHANN BARTEL
Keyword(s):  
Spherical Harmonics ◽  
Deformation Space ◽  
Neck Formation ◽  
Deformation Parameters ◽  
Fission Barriers ◽  
Spherical Harmonics Expansion ◽  
Left Right Asymmetry ◽  
Rotating Nuclei

A four-dimensional deformation space adapted to describe the fission dynamics of hot, rotating nuclei is proposed. The deformation coordinates consisting of the elongation, neck formation, left-right asymmetry and nonaxiality result in fission barriers much lower and thiner than those obtained in the spherical-harmonics expansion using the same number of deformation parameters.

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