1212.4980 (M. Greger et al.)

Isosbestic Points: Theory and Applications    [PDF]

M. Greger, M. Kollar, D. Vollhardt

We analyze the sharpness of crossing "isosbestic" points which are observed in many quantities described by a function f(x,p), where x is a variable (e.g., the frequency) and p a parameter (e.g., the temperature). We derive a simple criterion that needs to be fulfilled by f(x,p) to exhibit a sharp isosbestic point and relate it to the applicability of perturbation theory in p. Using this approach we explain the sharpness of crossing points in the optical conductivity sigma(omega,n) of the Falicov-Kimball model and the spectral function A(omega,U) of the Hubbard model. We also analyze isosbestic points in data for the Raman response chi(omega,T) of HgBa_2CuO_4+delta, photoemission spectra I(omega,T) of thin VO_2 films, and the reflectivity R(omega,T) of CaCu_3Ti_4O_12.

View original: http://arxiv.org/abs/1212.4980