Linear optical response of assemblies of small semiconductor spheres is studied by using a nonlocal theory. A self-consistent treatment of the Schrödinger and Maxwell equations naturally leads to complex radiative corrections to electronic levels. The size and the dimensionality dependence is examined from the response spectra and the matrix elements of the retarded interaction. For one and two dimensional infinite lattices of the spheres, it is shown analytically that the complex radiative corrections obtained by this semiclassical approach agree with those obtained by QED. The size dependence in finite systems is investigated numerically for some geometries. It is shown that the Coulomb interaction causes a strong geometry dependence of response spectra even if the system is much smaller than the wavelength of resonant light. The size-resonant enhancement of induced polarization is also investigated.

• Received 6 October 1994

DOI:https://doi.org/10.1103/PhysRevB.51.14379