The optical properties of copper and silver bulk crystals with atomically clean surfaces have been determined experimentally and interpreted in terms of ab initio band structure calculations. The dielectric functions are evaluated from spectroscopic ellipsometry data taken in ultrahigh vacuum ͑UHV͒ in the spectral range of 2.5-9.0 eV ͑at room temperature͒. The data are corrected for surface roughness using results from ex situ atomic force microscopy ͑AFM͒. Significant differences of detail in the amplitudes and line shape are attributed to the better surface quality of our samples. Density functional calculations of the dielectric functions of copper and silver are carried out, based on models of the valence bands deduced by fitting to experimental Fermi surface and quasiparticle mass data. Small energy shifts, which take into account many-body effects in the final states of the optical transitions in an extended scissors approximation, are needed to bring the calculated dielectric functions into good agreement with the experimental data. The interband transitions associated with individual features in the dielectric function are identified by comparing the energy derivatives of the measured and calculated dielectric functions.

We present an approach that takes into account lattice dynamical effects in calculating the optical response of semiconductors by averaging over several perturbed configurations of a supercell extracted from molecular dynamic simulations. The validity of this approach is confirmed by comparing our results for the dielectric function of bulk GaAs in the range of 0 - 700 K with our and other highly accurate ellipsometry measurements. The results of our approach resolve the serious discrepancy in energy and line shape between the latest optical models, all of which neglect lattice dynamics, and experiment

The conduction-electron g factor has been calculated at points on the Fermi surfaces of copper, silver, and gold by a relativistic linearized muffin-tin orbital method in the atomic-sphere approximation. The orbital g factors for principal extremal orbits on the Fermi surface of each metal have been deduced. A comparison with experimental g-factor «fata makes it possible to estimate the exchange-correlation enhancement factor for electrons on the Fermi surface of copper. The Fermisurface average of the enhancement factor is in agreement with the predictions of a first-principles calculation, and the data suggest a weak anisotropy. Experimental data for silver and gold prove to be insufFiciently accurate to yield reliable values of the exchange-correlation enhancement factor. A g-factor anomaly on the neck orbit in gold is discussed.

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