Large-amplitude motion

Bastiansen, O., Kveseth, K., and Mollendal, H. Structure of Molecules with Large Amplitude Motion as Determined from Electron-Diffraction Studies in the Gas Phase. 81, 99-172 (1979). 

The temperature dependent spectra of PBLG-d5 is shown in Fig. 6. Line shapes below — 76°C are similar to the rigid state pattern, indicating the absence of fast and large-amplitude motions. They are, however, different in... 

In order to understand the large amplitude motion, the allowed conformations brought about the multiple internal rotations were calculated for a single... 

The projections of a single side chain on the plane perpendicular to the helix axis are shown in Fig. 20(a), and the directions of a CK-2H bond are shown in Fig. 20(b). The C 2H bond vectors are distributed nearly symmetrically around the average direction. The same result was obtained for a Cf 2H bond. Therefore, jumps among multiple sites which are axially symmetric about the average direction are a good approximation for the large amplitude motion. 

In addition to the large amplitude motion, the libration is expected to exist at higher temperatures as well as at lower temperatures, so that the libration was taken into account as small angle three-site jumps. As a result, the C-2H bond undergoes motions superimposed with two independent three-site jumps. In the calculations, a 0 value of 14° at room temperature was used as the polar angle of the libration, and its distribution was not... 

Table 1. Parameters of large amplitude motions for PBLG-fd2...

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