The numerical solution to Poisson\´s equation under quasi-equilibrium conditions, using a formulation that includes carrier degeneracy, multiple conduction band minima, nonparabolicity of the Γ valley, and dopant deianization, is discussed. Moment theorems are shown to provide stringent tests for the accuracy of numerically simulated capacitance versus voltage characteristics. The numerical model is also used to quantify errors in a widely used technique for extracting band discontinuities by

analysis.