Vibration-internal rotation interaction and normal modes in nonrigid asymmetric top molecules: Application to trans-methylnitrite

1984 ◽  
Vol 104 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Pradip N. Ghosh ◽  
Sajal K. Ganguly
1967 ◽  
Vol 45 (12) ◽  
pp. 3867-3893 ◽  
Author(s):  
P. R. Bunker ◽  
J. T. Hougen

In 1964 Duncan determined force fields for the molecules CH3—C≡C—CH3 and CH3—C≡C—SiH3 under the assumption that the force constants were not dependent on the torsional angle γ. In the first half of this paper we determine the quantitative effect of adding various γ-dependent force constants to Duncan's force field for CH3—C≡C—CH3. The results lead to complications concerning the symmetry species of the normal coordinates, the magnitude of the Coriolis coupling constants, and the calculation of the energy levels. The possible avoidance of these complications is discussed.In the second half of the paper a formalism is set up relating the rotational and torsional centrifugal distortion constants to the vibrational force field for certain molecules with nearly free internal rotation. Duncan's force field for CH3—C≡C—SiH3 is used to calculate some centrifugal distortion constants for that molecule and for CH3—C≡C—SiD3 on the assumption of completely free internal rotation. Good agreement is obtained between the quantities calculated here and the observed quantities determined by Kirchhoff and Lide.


2008 ◽  
Vol 251 (1-2) ◽  
pp. 394-409 ◽  
Author(s):  
John C. Pearson ◽  
Carolyn S. Brauer ◽  
Brian J. Drouin

1965 ◽  
Vol 43 (5) ◽  
pp. 935-954 ◽  
Author(s):  
Jon T. Hougen

A method is presented for giving a precise meaning to the concept of a "normal mode" in dimethylacetylene for the limiting case of almost free internal rotation. The normal modes so defined are shown to transform according to irreducible representations of the molecular symmetry group discussed in a previous paper. In addition, the effect on the energy levels of Coriolis interaction between the vibrational motion and both the overall rotation and the torsion is discussed for doubly degenerate and quadruply degenerate vibrational states. Selection rules for transitions between the various Coriolis components are presented, which are analogous to the "(+l), (−l) selection rules" for "ordinary" symmetric-top molecules. The effect of a small barrier to internal rotation is discussed briefly.


2000 ◽  
Vol 179 ◽  
pp. 379-380
Author(s):  
Gaetano Belvedere ◽  
Kirill Kuzanyan ◽  
Dmitry Sokoloff

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan & Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.


1999 ◽  
Vol 4 (1) ◽  
pp. 6-7
Author(s):  
James J. Mangraviti

Abstract The accurate measurement of hip motion is critical when one rates impairments of this joint, makes an initial diagnosis, assesses progression over time, and evaluates treatment outcome. The hip permits all motions typical of a ball-and-socket joint. The hip sacrifices some motion but gains stability and strength. Figures 52 to 54 in AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fourth Edition, illustrate techniques for measuring hip flexion, loss of extension, abduction, adduction, and external and internal rotation. Figure 53 in the AMA Guides, Fourth Edition, illustrates neutral, abducted, and adducted positions of the hip and proper alignment of the goniometer arms, and Figure 52 illustrates use of a goniometer to measure flexion of the right hip. In terms of impairment rating, hip extension (at least any beyond neutral) is irrelevant, and the AMA Guides contains no figures describing its measurement. Figure 54, Measuring Internal and External Hip Rotation, demonstrates proper positioning and measurement techniques for rotary movements of this joint. The difference between measured and actual hip rotation probably is minimal and is irrelevant for impairment rating. The normal internal rotation varies from 30° to 40°, and the external rotation ranges from 40° to 60°.


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