Naslov
Dielectric properties of multiband electron systems: II - Collective modes

Autori
Županović, Paško ; Bjeliš, Aleksa ; Barišić, Slaven

Izvornik
Zeitschrift für Physik B (0722-3277) 101 (1996); 397-404

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
collective modes; Landau damping; dielectric instability

Sažetak
Starting from the tight-binding dielectric matrix in the random phase approximation we examine the collective modes and electron-hole excitations in a two-band electronic system. For long wavelengths (q->0), for which most of the analysis is carried out, the properties of the collective modes are closely related to the symmetry of the atomic orbitals involved in the tight-binding states. In insulators there are only inter-band charge oscillations. If atomic dipolar transitions are allowed, the corresponding collective modes reduce in the asymptotic limit of vanishing bandwidths to Frenkel excitons for an atomic insulator with weak on-site interactions. The finite bandwidths renormalize the dispersion of these modes and introduce a continuum of incoherent inter-band electron-hole excitations. The possible Landau damping of collective modes due to the presence of this continuum is discussed in detail.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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