ALPHA is a world-leading experiment that tests fundamental symmetries of physics through high-precision measurements on magnetically trapped antihydrogen atoms. ALPHA has over the past few years published high-profile articles on ,e.g., hyperfine spectroscopy, 1s-2s spectroscopy, laser cooling, and most recently the gravitational interaction of antihydrogen atoms. These results are compared to results for ordinary hydrogen, yielding stringent limits for matter-antimatter symmetries. Over the years I have supported the experiment with numerical simulations of antihydrogen formation through three-body collisions. These calculation were carried out at HPC2N, which is no longer available to me. In this project I will continue the work published in S Jonsell and M Charlton, "On the formation of trappable antihydrogen" 2018 New J. Phys. 20 043049. This work has renewed interest because of progress in sympathetic cooling of positrons in the ALPHA experiment. In agreement with the conclusions in our 2018 paper, this has led to a vast increase in the number of trapped antihydrogen atoms, which in turn makes more precise, as well as in the future completely new, studies possible. We are now preparing a publication based on experimental data from 2023. In doing this we want to complement our earlier numerical studies with more detailed simulations.