A perturbation treatment of Kubo's basic formula for the electrical-conductivity tensor is used to derive an expression for the Hall mobility of the small polaron. The result disagrees with those of other treatments based on Kubo's formula, but coincides completely with that obtained previously by the present authors via a jump-probability approach.
A new tunable source of the far-infrared radiation based on intersubband electronic Raman scattering in semiconductor quantum wells is proposed. The gain and threshold of the proposed Raman oscillator are estimated and compared with the intersubband laser.
A theory of acoustic-mode scattering has been formulated within the tight-binding approximation of band theory, and has been applied to narrow-band semiconduction in organic molecular crystals. The latter problem has been treated previously only in terms of phenomenological scattering parameters. The interaction constants are obtained explicitly as gradients of the characteristic overlap integrals. In addition, the wave-vector dependence of the matrix elements is taken into account. To first order in the (relative) displacements, the matrix elements include scattering by short-wavelength phonons, an essential feature of the narrow-band case not treated by conventional deformation-potential theory. The matrix elements physically represent variations of the band width and band centroid with relative displacement; in addition small (drag) terms proportional to the local lattice velocities are obtained. The theory is first applied to a onedimensional band model, for the case of both elastic and inelastic scattering. It is then applied to the basecentered-monoclinic structure, for which numerical estimates of the interaction constants have been made available by LeBlanc for anthracene.
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