The geometryXVx folder contains all the code describing methods which are specific to a geometry with 1 spatial dimension and 1 velocity dimension. It is broken up into the following sub-folders:

Boltzmann solver : Solvers for a Boltzmann equation.
Geometry X-Vx : All the dimension tags used for a simulation in the geometry.
Initialization methods : Initialization methods for the distribution function.
Quasi-Neutrality Solver : Code describing the Quasi-Neutrality solver.
RHS : Code describing the operators on the right hand side of the Boltzmann equation; namely sources, sinks and collisions.
Time integration : Time integrators for a Boltzmann-Poisson system of equations.
Utils : Miscellaneous utility functions.