How to choose the input parameters

In the previous module, you have been guided step-by-step through the calculations of an optical spectrum by solving the Bethe-Salpeter equation. The values for the relevant input parameters have then been given to you. In this module you will learn how to choose those parameters. These parameters are related either to the truncation of infinite sums or to the approximations of infinitesimal with small, but finite quantities. A wrong choice of these parameters can lead to inaccurate or even physically wrong results.

One then needs to run a series of calculations by changing the parameters till the results are 'converged' , meaning they are changing by a negligible amount.