Comment on ``Jellium model of metallic nanocohesion''
  In a recent letter Stafford, Baeriswyl and Burki have provided a simple model for the elastic force in metallic constrictions of nanometer size. By employing a semiclassical Weyl expansion for the density of states of transverse modes, we show that for any smooth cross section, there is a universal contribution (4 epsilon_F)/(9 lambda_F) to the average force which is absent in the presence of a hole. 
C. Hoeppler, W. Zwerger