Crystal structure and properties of iodine monofluoride compounds at high pressure

The pressure-induced structural phase transitions of halogen compound IF under high pressure were studied by using the unbiased CALYPSO structure prediction method. The phase transition sequence of IF under high pressure is determined to be P1 → P21/c-I → P21/c-II → I4/mmm, and the corresponding phase transition pressures are 3 GPa, 16.5 GPa and 46 GPa, respectively. The physical properties of each predicted phase were thus fully studied, and it was found that the P1 phase was unstable which is in excellent agreement with the experiment result. Furthermore, our exploration of the high pressure phases for IF will provide fundamental insights for further exploration the structural phase transition of other halogen compounds under high pressure.