Strong-Coupled Piezoelectric Polaron

A semiclassical, variational calculation for the strong-coupled piezoelectric polaron gives the following results for the ground-state energy and polaron radius, respectively: U₀=-0.47(m*m)(κ²ε)² eV, and R=3.5(εκ²)(mm*) , where m* is the band effective mass, κ is the electromechanical coupling constant, and ε is the strain-free dielectric constant. The theory is expected to be valid when |U₀| is larger than thermal energies and R is considerably larger than unit-cell dimensions. A calculation of the polaron effective mass, having a more limited region of validity, gives mₚ≈m*[1+2|U₀|m*vₛ²], where vₛ is the velocity of sound.