How are the simulated powder diffraction patterns calculated?

The calculation used to simulate powder diffraction patterns in Mercury is fundamental thus no one algorithm exists, rather a series of steps need to be taken based on the theories of how X-rays interact with 3-D lattices. The publication "Fundamentals of Crystallography" by C. Giacovazzo, H. L. Monaco, D. Viterbo, F. Scordari, G. Gilli, G. Zanotti, M. Catti by Oxford University Press and the IUCr (ISBN 0 19 855578 4) gives a good overview of the steps required to generate a simulated powder diffraction pattern.​