Here, we investigate and discuss the effects of H-induced lattice relaxation on the H absorption into (desorption from) a Li(100) surface. Using the coupled-channel method via the local reflection matrix scheme, we performed quantum dynamics calculations to obtain the H absorption and desorption probability plots as functions of the H initial translational energy and the Li initial vibrational state. Our results show that the hydrogen motion and the surface lattice relaxation are dynamically coupled and, depending on the initial conditions, the surface lattice motion either promotes or hinders the penetration of hydrogen into (desorptin from) the surface (subsurface). At low initial translational energy of H, the Li lattice has sufficient time to relax effectively reducing the energy barrier for H absorption and desorption
