The search for high-temperature superconductors has been focused on compounds
containing a large fraction of hydrogen, such as SiH4 (H2) 2, CaH6 and KH6. Through a
systematic investigation of yttrium hydrides at different hydrogen contents using an structure
prediction method based on the particle swarm optimization algorithm, we have predicted
two new yttrium hydrides (YH4 andYH6), which are stable above 110 GPa. Three types of
hydrogen species with increased H contents were found, monatomic H in YH3, monatomic …