  The prediction of reaction pathways for solid-solid transformations remains a
key challenge. Here, we develop a pathway sampling method via swarm
intelligence and graph theory, and demonstrate that our PALLAS method is an
effective tool to help understand phase transformations in solid-state systems.
The method is capable of finding low-energy transition pathways between two
minima without having to specify any details of transition mechanism a priori.
We benchmarked our PALLAS method against known phase transitions in cadmium
selenide (CdSe) and silicon (Si). PALLAS readily identifies
previously-reported, low-energy phase transition pathways for the wurtzite to
rock-salt transition in CdSe and reveals a novel lower-energy pathway that has
not yet been observed. In addition, PALLAS provides detailed information that
explains the complex phase transition sequence observed during the
decompression of Si from high pressure. Given the efficiency to identify
low-barrier-energy reaction pathways, the PALLAS methodology represents a
promising tool for materials by design with valuable insights for novel
synthesis.
