When we perform an LO with ONETEP we want to ensure a good balance between speed and precision with respect to the LM being explored. We found that by allowing a reasonably loose force criteria (0.3 eV/ Å) we were able to quickly converge structures to a reasonable approximation of the LM and allow the GO, conducted by pyGlobOpt , to optimise these structures further. We note that the timings of the later structures significantly improved over the course of the run (c.f. section S10) indicating better initial starting structures.