\( \xi ^{ 2 }=\cfrac { 1 }{ 2 } (1-\cfrac { 1 }{T_{ o }} )\)
and
\(T_{ o } >1 \)
the system is always underdamped.
According to conventional description, it is consistent that,
the region above the kink is the conduction band. The region below the kink is the valence band. Normally, room temperature is below the kink, most electrons are in the valence band. Electrons get trapped in the conduction band because a quantum of energy is needed to fall back into the valence band (ref: "Post Pag.Pag...Pag....Pag Dnab Ygrene"). Such electron contributes to the conductivity of the material. The same quantum of energy also represents the energy band gap between the conduction and valence band.
