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• DFT and AIMD were combined to study the oxidation mechanism of CrN. • Surface energy of CrN low-index surface was calculated. • The adsorption configuration and electronic structure were analyzed. • The dynamics process of O 2 dissociation and adsorption was studied by AIMD. • The PDOS change during AIMD simulation were analyzed. [Display omitted] Density functional theory (DFT) calculation and ab initio molecular dynamics (AIMD) are combined to investigate the CrN oxidation mechanism. The surface energy, adsorption configuration and electronic structure of oxygen molecule and atom on the CrN (100) surface are investigated through DFT calculation. AIMD calculation is used to investigate the geometric configuration and electronic structure evolution of O 2 molecule adsorption and dissociation process at 1073 K. Results show that the (100) surface has the lowest surface energy. The top site of Cr atom is the most stable adsorption site for oxygen molecules and atoms, and the adsorption energy values are −4.276 eV and −4.975 eV, respectively. Charge density difference results show that both oxygen molecule and atom undergo charge transfer with the Cr atom. The O atom gains electrons while the Cr atom loses electrons. Results of partial density of states show that the Cr O bond is formed due to the hybridization between the O-p and Cr-d orbitals. At 1073 K, AIMD results show that the O 2 molecule automatically dissociates into O atoms, and the dissociated O atoms form stable covalent bonds with the surface Cr atom. The hybridization between the O-p and Cr-d orbitals gradually increases, thereby forming stable adsorption. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) and ab initio molecular dynamics (AIMD) calculations are combined to study the α-Ti oxidation mechanism on atomic scale. The most and second stable adsorption site for O atoms on the surface layer is FCC and HCP site, respectively. The most stable adsorption site of subsurface layer is octahedral site. O atoms all gain electrons from adsorbed Ti atoms and the Ti–O bonds are mainly formed by the hybridization between O-p and Ti-d orbitals. At both 303 K and 873 K, AIMD results show that O 2 molecule gradually dissociate into O atoms on α-Ti (0001) surface and then adsorb on the surface. The increase of temperature accelerates the dissociation rate of O 2 molecule. During the formation of Ti–O bond, O and Ti atom gain and lose electrons, respectively. The partial density of states evolution results show that the Ti–O bond is formed by the gradually strengthened hybridization between O-p and Ti-d orbitals. At 303 K, α-Ti (0001) surface can form a dense oxide film. But a discontinuous and loose oxide film is formed at 873 K and O atoms can penetrate into the octahedral and tetrahedral sites of the subsurface layer. • DFT and AIMD were combined to reveal the α-Ti oxidation mechanism. • Adsorption behavior of O atom on surface and subsurface was studied by DFT. • The dynamic dissociation and adsorption process of O 2 was investigated by AIMD. • The temperature effect on the O 2 dissociation behavior was studied by AIMD. • Electronic structure during DFT and AIMD calculation were investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT and AIMD were combined to study the Ti 2 AlC oxidation mechanism. • Surface energy of different Ti 2 AlC (0001) surfaces was calculated. • The adsorption configuration and electronic structure were analyzed. • The dynamics process of O 2 dissociation and adsorption was investigated by AIMD. • The PDOS changing process during AIMD simulation was analyzed. Ti 2 AlC oxidation mechanism was investigated by density functional theory (DFT) and ab initio molecular dynamics (AIMD). DFT results showed that the most stable adsorption site was HCP hollow sites, followed by FCC. O atom gained electrons, while Al atom lost electrons through the hybridisation of O-p and Al-s/p orbitals. AIMD results show that O 2 molecule gradually dissociated into O atoms at 1273 K and formed Al-Ti mixed oxide film. The hybridisation between O-p and Al-s/p orbitals formed Al-O bond, while the hybridisation of O-p and Ti-d orbitals formed Ti-O bond. [ABSTRACT FROM AUTHOR]