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A Microscopic Theory for the Central Peak in Hydrogen‐Bonded Ferroelectrics
Author(s) -
Wesselinowa J. M.,
Apostolov A. T.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199706)201:2<529::aid-pssb529>3.0.co;2-f
Subject(s) - transverse plane , coupling (piping) , condensed matter physics , phonon , mechanism (biology) , microscopic theory , quantum tunnelling , mode coupling , longitudinal mode , materials science , hydrogen , function (biology) , mode (computer interface) , soft modes , physics , ferroelectricity , quantum mechanics , composite material , structural engineering , dielectric , evolutionary biology , computer science , engineering , biology , operating system , laser
A microscopic theory for the central peak in hydrogen‐bonded ferroelectrics is given. The transverse Ising model is treated by means of a Green's function technique to calculate the dynamical structure factor. It can be separated into three terms, which determine different mechanisms of the formation of the central peak: the relaxational mechanism, due to the coupling between the transverse soft mode and the longitudinal mode, the oscillatory mechanism, caused by the coupling between the transverse soft mode and the phonon mode, the third — “mixed” mechanism — can be treated as an effective coupling between the phonon and the longitudinal modes. The relaxational mechanism predominates in all hydrogen‐bonded ferroelectrics, while the “mixed” mechanism plays an important role in ferroelectrics with a large value of the tunneling frequency Ω, such as KDP and RDP.