Specificity of $\tau$ -- approximation for chaotic electron trajectories on complex Fermi surfaces

The work examines a special behavior of the magnetic conductivity of metals that arises when chaotic electron trajectories appear on the Fermi surface. This behavior is due to the scattering of electrons at singular points of the dynamic system describing the dynamics of electrons in $\, {\bf p}$-space, and caused by small-angle scattering of electrons on phonons. In this situation, the electronic system is described by a "non-standard" relaxation time, which plays the main role in a certain range of temperature and magnetic field values.