3.2 Equilibrium Finite Temperature GREEN's Function

In Section 3.1 the GREEN's function for a system under equilibrium at zero temperature has been introduced. Furthermore, the GREEN's function was readily expressed as perturbation expansion in the interaction picture. In this section, the GREEN's function for a system under equilibrium at finite temperature is presented. The GREEN's function at finite temperature has a simple perturbation expansion similar to that for the GREEN's function at zero temperature and also enables us to evaluate the properties of the system.
M. Pourfath: Numerical Study of Quantum Transport in Carbon Nanotube-Based Transistors