A Fortran code for solving the Kadanoff–Baym equations for a homogeneous fermion system Original Research Article

A Fortran code for solving the Kadanoff–Baym equations for a homogeneous fermion system is presented. These are a class of quantum kinetic equations the solutions of which are two-time Green (correlation) functions, which carry both statistical (orbital occupation distributions) and dynamical (orbital energies and widths) information about the system away from equilibrium. In this program, the systemʹs initial state is assumed to be uncorrelated. As examples of applications, two separate situations involving equilibration (thermalization) are considered: the first one models an electron plasma in an excited semiconductor, and the other models nuclear heavy-ion collisions. The most time-consuming part of the program is the computation of the convolutions of various combinations of the Green functions. This task is efficiently performed by the use of Fast Fourier Transform. As summary output, the particle density, energy densities, and the quadrupole moment of the distribution are displayed. The program can easily be modified such that the user may use any initial distribution of fermions.