The NNIP is for the ternary $\alpha$-Fe-C-H system, it can well describe interactions of H/C with perfect and defective $\alpha$-Fe, H with cementite, H with ferrite-cementite interface, also works well for $\alpha$-Fe, hydrogen gas. please cite: a paper which has been accepted by JOM entitled: Machine-learning Interatomic Potentials for the Ternary α-Fe–C–H System: Toward Million-Atom Simulations of Hydrogen Embrittlement in Steel