Title: TO THE THEORY OF RELAXATION PHENOMENA IN QUASI-ONE-DIMENSIONAL FERROELECTRICS WITH HYDROGEN BONDS. NONEQUILIBRIUM STATISTICAL OPERATOR APPROACH
Authors:R.R.Levitskii, I.R.Zachek, R.O.Sokolovskii (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine 1 Svientsitskii St., 290011 Lviv-11, Ukraine)

Kinetic equations for the dielectric properties of CsH$_{\bf{}2}$PO$_{\bf{}4}$-type ferroelectrics are derived within the nonequilibrium statistical operator method proposed by D.N.Zubarev. These equations are solved with two different approaches. In the first approach the closure relation in the spirit of a two-site cluster approximation is used. In the second approach the exact relation between the static correlation functions is extrapolated to a dynamic case and used as a closure relation. The both approaches give similar results. The obtained dynamic characteristics are close to those of the Glauber model and are shown to describe the dynamic dielectric permittivity of CsH$_{\bf{}2}$PO$_{\bf{}4}$ and CsD$_{\bf{}2}$PO$_{\bf{}4}$ crystals.

Key words: nonequilibrium statistical operator, kinetic equation, order-disorder ferroelectrics, dynamic permittivity
Comments: Figs. 2, Refs. 52, Tabs. 2.