The three halogen solids(Cl_(2),Br_(2),and I_(2))have the isostructural diatomic molecular phaseⅠwith a space group of Cmca at ambient pressure.At high pressure,they all go through an intermediate phaseⅤwith incomme...The three halogen solids(Cl_(2),Br_(2),and I_(2))have the isostructural diatomic molecular phaseⅠwith a space group of Cmca at ambient pressure.At high pressure,they all go through an intermediate phaseⅤwith incommensurate structures before eventually dissociating into the monatomic phaseⅡ.However,a new structural transition between phaseⅠandⅤwith anomalous bond-length behavior was observed in bromine under pressure,which,so far,has not been confirmed in iodine and chlorine.Here,we perform first-principles calculations for iodine and chlorine.The new structural transition was predicted to be common to all three halogens under pressure.The transition pressures might be systematically underestimated by the imperfect van der Waals correction method,but they follow the order Cl_(2)>Br_(2)>I_(2),which is consistent with other pressure-induced structural transitions such as metallization and the molecular-to-monatomic transition.展开更多
基金the National Natural Science Foundation of China(Grant Nos.51701180,51871201,U1802254)。
文摘The three halogen solids(Cl_(2),Br_(2),and I_(2))have the isostructural diatomic molecular phaseⅠwith a space group of Cmca at ambient pressure.At high pressure,they all go through an intermediate phaseⅤwith incommensurate structures before eventually dissociating into the monatomic phaseⅡ.However,a new structural transition between phaseⅠandⅤwith anomalous bond-length behavior was observed in bromine under pressure,which,so far,has not been confirmed in iodine and chlorine.Here,we perform first-principles calculations for iodine and chlorine.The new structural transition was predicted to be common to all three halogens under pressure.The transition pressures might be systematically underestimated by the imperfect van der Waals correction method,but they follow the order Cl_(2)>Br_(2)>I_(2),which is consistent with other pressure-induced structural transitions such as metallization and the molecular-to-monatomic transition.
