Effect Of Umklapp Research Articles

Calculation of Local Effective Fields: Optical Spectrum of Diamond

The random-phase-approximation formalism describing local fields developed by Adler and by Wiser is evaluated for an insulator for the first time. It is shown that umklapp effects decrease the low-frequency electronic dielectric constant, contrary to what is required to reconcile theory with experiment for most semiconductors. A simple prescription for effects of dynamical correlation is shown to improve agreement with experiment for diamond.

Calculation of Local Effective Fields: Optical Spectrum of Diamond

The random-phase-approximation formalism describing local fields developed by Adler and by Wiser is evaluated for an insulator for the first time. It is shown that umklapp effects decrease the low-frequency electronic dielectric constant, contrary to what is required to reconcile theory with experiment for most semiconductors. A simple prescription for effects of dynamical correlation is shown to improve agreement with experiment for diamond.

Effect of Umklapp on the low temperature electrical resistivity of nonmagnetic dilute alloys

The deviation from Matthiessen's rule recently studied by Caplin and Rizzuto on Al based alloys is explained as an effect of the anisotropy of the Fermi surface on electon-phonon and electron-impurity scattering. Use is made of the diffusion theory of electrons by Klemens and Jackson.