Effect of hydrogen atoms adsorption on the work function of the LaB6

• The work function, dipole moment, DOS and adsorption energy for H adsorption on LaB 6 were calculated. • As H coverage increases, both the average adsorption energy and work function increase. • The work function decreases linearly with the increase of dipole moment density. • H atom form a dipole moment pointing to the surface, increasing the work function. This study employed first-principles density functional theory using CP2K and VASP software to investigate the effects of hydrogen atoms adsorption on the work function of the LaB 6 (001) surface. These results indicate that the most favorable adsorption site for hydrogen atoms is located on the top of the boron atoms in the center of the cell. As the hydrogen atom coverage density increases, the absolute value of the average adsorption energy decreases, while the surface work function gradually increases. The analysis shows that changes in the work function are strongly correlated with variations in dipole moment density, exhibiting a linear relationship. Furthermore, charge transfer induced by LaB 6 substrate deformation, the intrinsic charge carried by the hydrogen adsorbate, and the charge transfer resulting from the interaction between the hydrogen adsorbate and the LaB 6 surface substrate determine the variations in dipole moment. When the hydrogen coverage density is below 8.54 × 10 -2 atoms / Å 2 , its effect on the material’s work function is relatively small, with the work function increasing from 2.14 eV to 2.47 eV. It is expected that this study can serve as a reference and theoretical basis for preliminary explorations into the application of LaB 6 in the NBI system.