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Updated: Oct 21, 2025

Atomic Scale Structural Studies of Macromolecular Assemblies by Solid-state Nuclear Magnetic Resonance Spectroscopy
Published on: September 17, 2017
Second harmonic generation theory for a helical macromolecule with high sensitivity to structural disorder
Darius Abramavicius1, Serguei Krouglov2,3, Virginijus Barzda2,3,4
1Institute of Chemical Physics, Vilnius University, Sauletekio al. 9-III, 10222 Vilnius, Lithuania. darius.abramavicius@ff.vu.lt.
Abstract:
Microscopic theory for the second harmonic generation in a helical molecular system is developed in the minimal coupling representation including non-local interaction effects. At the second order to the field we find a compact expression which combines dipolar, quadrupolar and magnetic contributions. A detailed derivation of the response is performed to specifically isolate the quadratic coupling terms, which we denote as the K coupling. Applying the theory to a helical macromolecule we find that the dipolar and quadrupolar contributions reflect the symmetry properties of the system and its homogeneity, while the K coupling contribution reveals inhomogeneities of the system.
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