In Section 2, the analytical expressions for the dispersion relation, correlated Debye frequency and temperature, and three first XAFS cumulants have been derived.
Then, we can describe the system in the present ACDM involving all different frequencies up to the Debye frequency as a system consisting of many bodies, that is, many phonons, each of which corresponds to a wave having frequency &(q) and wave number q varied in the first BZ.
At the bounds of the first BZ of the linear chain, q = [+ or -] [pi]/[alpha], the frequency is maximum so that from (8), we obtain the correlated Debye frequency [[omega].sub.D] and temperature [[theta].sub.D] in the form
The values of local force constant [k.sub.eff], correlated Debye frequency [[omega].sub.D], and temperature [[theta].sub.D] calculated using the present theory are given in Table 2.
Along with the Debye temperature it is used the concept of the Debye frequency
([[omega].sub.D]), momentum ([P.sub.D]), wavelength, or more precisely the Debye wave ([[lambda].sub.D]), as well as the Debye energy.
where [[Omega].sub.o], the attempt frequency, is on the order of the Debye frequency; [Delta][F.sub.f] is the activation free energy for the transformations; k is the Boltzmann constant; and T is the absolute temperature.
We also note that the fundamental attempt frequency, [[Omega].sub.o], is on the order of the Debye frequency ([10.sup.11] to [10.sup.13] [s.sup.-1]) and we shall use a value of [10.sup.11] [s.sup.-1] without any adjustment.