Gauge treatment of the intra-collisional-field-effect in electron transport theory

We study the evolution equations of the distribution functions of hot electrons. We show that a convenient choice of the gauge describing the applied uniform electric and magnetic fields considerably simplifies the explicit calculations. The main advantage of our method lies in the possibility of treating with the same simplicity free electrons (with or without a magnetic field) and Bloch electrons (without a magnetic field). We discuss the influence of the electric field on the collision term of the different transport equations we derive.