How can I calculate the angular (2theta) resolution of powder XRD for a given instrument/configuration? What are the limiting factors, and what are good stategies to optimize the angular resolution?
There is the so-called fundamental parameters approach, which allows simulating the instrumental profile function as a function of the settings of the diffractometer. It is in particular frequently applied to to standard Bragg-Brentano instruments. Do a google search ("fundamental parameters approach" diffraction"). The classic Cheary&Coelho paper which I found there will help you to proceed. The paper of course mentioned the various influencing factors which could help you optimising the angular resolution.