Level spacing statistics and far-infrared absorption in small metal clusters

Calculated level spacing statistics in randomly shaped jellium metal clusters, with Coulomb and Breit interactions between the electrons, is found to differ qualitatively from the Wigner distribution and better correspond with the Poisson distribution. Prediction of significantly enhanced far-infrared absorption is in excellent accord with experimental observations. Breit interaction is identified as key to the semi-metallic behavior persistent in small metal clusters at energy scales much lower than the average level spacing