Normal Mode Expansion in Neutron Thermalization Theory with a Simple Scattering Kernel

1971 ◽  
Vol 8 (3) ◽  
pp. 153-161 ◽  
Author(s):  
Tomejiro YAMAGISHI
Keyword(s):  
Normal Mode ◽  
Mode Expansion ◽  
Neutron Thermalization ◽  
Scattering Kernel

scholarly journals Quasi-normal mode expansion as a tool for the design of nanophotonic devices

2020 ◽  
Vol 238 ◽  
pp. 05008
Author(s):  
Rémi Colom ◽  
Felix Binkowski ◽  
Fridtjof Betz ◽  
Martin Hammerschmidt ◽  
Lin Zschiedrich ◽  
...  
Keyword(s):  
Normal Mode ◽  
Optical Antennas ◽  
Far Field ◽  
Riesz Projection ◽  
Mode Expansion ◽  
Nanophotonic Devices ◽  
Matter Interaction ◽  
Quasi Normal Mode ◽  
Light Matter Interaction

Many nanophotonic devices rely on the excitation of photonic resonances to enhance light-matter interaction. The understanding of the resonances is therefore of a key importance to facilitate the design of such devices. These resonances may be analyzed by use of the quasi-normal mode (QNM) theory. Here, we illustrate how QNM analysis may help study and design resonant nanophotonic devices. We will in particular use the QNM expansion of far-field quantities based on Riesz projection to design optical antennas.

scholarly journals On the Motion of Small Spheres in Gases. I. General Theory

1972 ◽  
Vol 27 (12) ◽  
pp. 1798-1803 ◽  
Author(s):  
M.M.R. Williams
Keyword(s):  
Specular Reflection ◽  
Mean Free Path ◽  
Accommodation Coefficient ◽  
Spherical Particles ◽  
Surface Scattering ◽  
Scattering Rate ◽  
Tangential Momentum Accommodation Coefficient ◽  
Neutron Thermalization ◽  
Tangential Momentum ◽  
Scattering Kernel

AbstractWe have developed a global scattering kernel which describes the scattering of gas atoms by spherical particles which are small compared with a mean free path in the gas. The global kernel, which is analogous in many ways to the thermal neutron scattering kernel employed in neutron thermalization studies, is given in terms of the gas-surface scattering law for the particle. Thus the global kernel can be studied as a function of specular reflection and incomplete accommodation. The recent model of KUŠČER and of CERCIGNANI is used for the latter investigation and we find that on the average the angular distribution of the scattered gas atoms depends sensitively on the tangential momentum accommodation coefficient but only very weakly on the energy coefficient. However, the phenomenon is strongly dependent on the speed of the approaching gas atom and, for low speed gas atoms, the sensitivity to energy accommodation becomes much more important. The net scattering rate is obtained and put in a form convenient for later calculations to be described in a series of companion papers.

Theoretical Investigation of the Jahn-Teller Vibronic 1E ⊗ ɛ State in the Neutral Vacancy of Silicon

1985 ◽  
Vol 63 ◽  
Author(s):  
J. C. Malvido ◽  
P. V. Madhavan ◽  
J. L. Whitten
Keyword(s):  
Normal Mode ◽  
Electronic States ◽  
Force Constants ◽  
Matrix Elements ◽  
Vibronic State ◽  
Irreducible Tensor ◽  
Mode Expansion ◽  
Tensor Methods ◽  
Jahn Teller ◽  
Vibronic States

ABSTRACTA method for constructing Jahn-Teller coupled vibronic states is developed by projecting distorted electronic eigenstates onto undistorted states and, with the aid of irreducible tensor methods, the force constants can be identified with reduced matrix elements of the normal mode expansion of the vibrational Hamiltonian. A scheme is then realized for estimating the force constants as well as the total vibronic energy from the calculated energie of the distorted electronic states. An application of the method to the 1 E ⊗E vibronic state of the neutral silicon vacancy is presented as an illustration

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