Optical properties of the Q1D multiband models -- the transverse   equation of motion approach
  The electrodynamic features of the multiband model are examined using the transverse equation of motion approach in order to give the explanation of several long-standing problems. It turns out that the exact summation of the most singular terms in powers of $1/\omega^{n}$ leads to the total optical conductivity which, in the zero-frequency limit, reduces to the results of the Boltzmann equation, for both the metallic and semiconducting two-band regime. The detailed calculations are carried out for the quasi-one-dimensional (Q1D) two-band model corresponding to imperfect charge-density-wave (CDW) nesting. It is also shown that the present treatment of the impurity scattering processes gives the DC conductivity of the ordered CDW state in agreement with the experimental observation. Finally, the DC and optical conductivity are calculated numerically for a few typical Q1D cases. 
Ivan Kupcic and Slaven Barisic