On the calculation of spectral density functions for spin interactions without axial symmetry

✍ Scribed by Canet, Daniel

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 137 KB
• Volume: 10
• Category: Article
• ISSN: 1043-7347
• DOI: 10.1002/(sici)1099-0534(1998)10:5<291::aid-cmr2>3.0.co;2-s

✦ Synopsis

Decomposition of an arbitrary cartesian tensor expressed in its principal axis system into two axially symmetric cartesian tensors greatly facilitates the calculation of spectral densities, the latter being the Fourier transform of correlation functions involving ( ) elements of those tensors. A straightforward method is given for two motional models: a ( ) fully anisotropic diffusion rotation, appropriate for rigid molecules; and b the ''model-free approach,'' appropriate for large molecules whose overall reorientation is slow and isotropic, and which undergo, in addition, fast local motions. Although of general applicability, these calculations are devoted here to the chemical shift anisotropy relaxation mechanism, especially in cross-correlation spectral densities involving the dipolar interaction.