Structural, electronic, and magnetic properties of the possible pnictide superconductor BaFeAs2

Iron-based superconductors have sparked a large amount of research, but the comprehensive studies on the 112 family are still lacking. ${\mathrm{BaFeAs}}_{2}$ has been predicted as a promising candidate of an iron-based superconductor. Here we systematically study its stability, electronic structures, and magnetic orders from the first-principles calculations. According to the stacking manners and As distortion in the [${\mathrm{Ba}}_{2}{\mathrm{As}}_{2}$] layer, four possible ${\mathrm{BaFeAs}}_{2}$ structures with $P4/nmm$, ${P2}_{1}/m$, $I4/mmm$, and $I2mm$ symmetry are constructed. The calculations demonstrate that the most stable structure is determined to be $I2mm$ symmetry, with the structure and valence state in [${\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$] layers closely resembling the characteristics of iron-based superconductors, as well as the electronic properties and stripe antiferromagnetic ground state. These findings are helpful for further research and comprehensive understanding of the 112-type iron-based superconductors.