scholarly journals A General Matrix Method for Treating Elastic Constants of Molecular Crystals; Application to Orthorhombic Polyethylene

1971 ◽  
Vol 44 (9) ◽  
pp. 2371-2378 ◽  
Author(s):  
Yuji Shiro ◽  
Tatsuo Miyazawa
Keyword(s):  
Elastic Constants ◽  
Matrix Method ◽  
Molecular Crystals ◽  
General Matrix

Elastische und thermoelastische Konstanten des rhombischen α-Schwefels

1969 ◽  
Vol 24 (5) ◽  
pp. 865 ◽  
Author(s):  
S. Haussühl
Keyword(s):  
Thermal Expansion ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Molecular Crystals ◽  
Organic Molecular Crystals ◽  
Anisotropy Of Thermal Expansion ◽  
Cauchy Relations

Abstract The elastic and thermoelastic constants of α-sulphur are measured by the Schaefer-Bergman method. The magnitude of the elastic constants is slightly higher than in comparable organic molecular crystals. The elastic anisotropy and the anisotropy of thermal expansion obey the Grüneisen relation. The deviations from the Cauchy relations are all negative. This is usually only observed in crystals with covalent bind­ing components or with a highly anharmonic behaviour.

Equations de bilan dépendentes du temps appliquées aux collisions inélastiques

1982 ◽  
Vol 60 (5) ◽  
pp. 654-658
Author(s):  
A. Lupaşcu ◽  
St. Tudorache ◽  
I. M. Popescu
Keyword(s):  
Cross Sections ◽  
Matrix Method ◽  
Inelastic Collisions ◽  
Time Dependent ◽  
Rate Equations ◽  
General Matrix ◽  
Dependent Rate ◽  
Minimal Information

A general matrix method for the time dependent rate equations applied to inelastic collisions is presented. The minimal information needed to compute the collisional cross-sections is deduced and used to study the particular case of two excited levels.

Dynamic Theory of Asymetric X-Ray Diffraction for Strained Crystal Wafers

1987 ◽  
Vol 31 ◽  
pp. 161-165 ◽  
Author(s):  
D. W. Berreman ◽  
A. T. Macrander
Keyword(s):  
Numerical Solution ◽  
Matrix Method ◽  
Dynamic Theory ◽  
Grazing Incidence ◽  
Dynamical Theory ◽  
Matrix Approach ◽  
X Ray Diffraction ◽  
General Matrix ◽  
X Ray ◽  
Strained Crystal

A very accurate 8X8 matrix approach to dynamical theory of X-ray diffraction in which fewer approximations are made than in the classic vonLaue approach, is described here. The method is related to the very general matrix method of Kokushima and Yamakito, and is particularly suited to numerical solution with a computer. It can be used to solve problems in ideal, undistorted crystals with high precision even at near grazing incidence without special consideration of refraction or external reflection. It is also easy to apply to problems where periodicity of oblique Bragg planes varies in the direction normal to the surface. Such strain may be induced, for example, by variation of composition with depth. Certain problems wherein simultaneous diffraction by two sets of Bragg planes occurs can also be treated by this approach.

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