Electronic, Mechanical, and Infrared Properties of BiOX (X = Cl, Br, I) Monolayers.

BiOX (X = Cl, Br, I) monolayers are photocatalytic materials having many potential applications, but their basic properties are still not systematically studied. Herein, first‐principles calculations are performed to study their electronic, mechanical, and infrared properties. Band structures calculated by the Heyd–Scuseria–Ernzerhof (HSE06) functional with and without spin orbital coupling uncover that they are indirect bandgap materials. Partial densities of states of these materials are computed and compared to reveal the reason for the differences among their band structures. Studies imply that the BiO bonds are chiefly covalent while the interaction between the Bi and the X atoms is mainly ionic. Elastic constants and ideal in‐plane stresses of these materials are computed to explore their mechanical properties. Performed factor group analyses indicate that there are nine Raman‐active and six infrared‐active modes in their Brillouin zone centers. Their infrared spectra are simulated and the reason for the disappearance of some infrared peaks is given. Comparisons on the above properties are also made for these BiOX monolayers. [ABSTRACT FROM AUTHOR]