Sampling eigenmodes in colloidal solids
  We study the properties of correlation matrices widely used in the characterisation of vibrational modes in colloidal materials. We show that the eigenvectors in the middle of the spectrum are strongly mixed, but that at both the top and the bottom of the spectrum it is possible to extract a good approximation to the true eigenmodes of an elastic system. 
A. C. Maggs and M. Schindler
cond-mat.soft