Low-temperature thermal conductivity of glasses within the soft-potential model

The low-temperature T-2 rise and the subsequent plateau of the thermal conductivity of glasses allow one to determine two parameters of the phenomenological soft-potential model. The first of these is a weighted average (C) over bar of the dimensionless parameter combinations C-l and C-t which the soft-potential model shares with the tunneling model. The second is the crossover energy W between tunneling states and vibrations. Values of W and (C) over bar obtained from the thermal conductivity of ten different glasses agree within experimental error with those obtained from specific-heat and acoustic-absorption data.