Plasmons in imperfect parabolic quantum-well wires: Self-consistent calculations

The effects of deviations from the bare perfect parabolic confining potential of a quantum-well wire on the dispersion relations of quasi-one-dimensional plasmons are studied. We calculate self-consistently the ground state in the Hartree approximation and the density response in the random-phase approximation. We find that for a bare perfect parabolic potential, one intersubband mode, the fundamental or Kohn’s mode, is pinned at the bare harmonic oscillator frequency independent from the electron density. It is shown that small nonparabolic imperfections shift the fundamental mode to higher or smaller frequencies and depend on the electron density.