Ab initio investigation of structural, electronic and magnetic properties of OH-functionalized monolayer CrX2 (X = S, Se, Te)

Abstract

In this study, density functional theory (DFT) calculations within the generalized gradient approximations
(GGA) were employed to investigate the structural and electronic properties of
CrX2 (X = S, Se, Te) monolayers in the octahedral (1T) phase using Quantum ESPRESSO. The
influence of adsorbed OH groups on these properties was also examined. The calculations reveal
that bond lengths, curvatures, and lattice constants increase with increasing chalcogen atomic
number (X), while structural stability decreases. Interestingly, OH group adsorption lowers the
total energy for all CrX2 monolayers, indicating enhanced stability, with the highest stability
observed for configurations with two adsorbed OH groups. Furthermore, the electronic properties
were studied by analyzing the band structures of CrX2 monolayers with and without OH groups
across non-magnetic, ferromagnetic, and antiferromagnetic states. While pristine monolayers
exhibit metallic behavior in all magnetic states, the introduction of OH groups leads to diverse
electronic behaviors. Additionally, the stable magnetic phases of the monolayers were determined
in the presence and absence of OH groups.