Vibrational instability, two-level systems, and the boson peak in glasses
Vibrational instability, two-level systems, and the boson peak in glasses
We show that the same physical mechanism is fundamental for two seemingly different phenomena such as the formation of two-level systems in glasses and the boson peak in the reduced density of low-frequency vibrational states $g(\ensuremath{\omega})∕{\ensuremath{\omega}}^{2}$. This mechanism is the vibrational instability of weakly interacting harmonic modes. Below some frequency …