Set maximum number of iterations for thermal equilibrium and charge neutrality calculation at each spatial step. If this quantity is set to zero then a constant temperature run will result, and charge neutrality will not be calculated. If this quantity is negative, then charge neutrality will be calculated, but thermal equilibrium will not. Default value is 0. Normal thermal equilbrium models can be calculated with niter=99, although the code seldom requires more than a few iterations (10 or 20 at most) to achieve thermal equilibrium under normal conditions.