Activated molecular adsorption of CO on the Be (0001) surface: A density-functional theory study

Using first-principles calculations, we systematically study the adsorption behaviors of molecular CO on the Be (0001) surface. By calculating the potential energy surfaces, we find that CO molecularly adsorbs on the Be surface with small energy barriers. The most stable adsorption state is found to be the one at the surface fcc hollow site, and the one at the surface top site is the adsorption state that has the smallest energy barrier. Based on electronic structure analysis, we further reveal that during the molecular adsorption, the $5\sigma$ bonding and $2\pi$ antibonding orbitals of CO hybridize with $s$ and $p_z$ electronic states of Be, causing electrons to transfer from CO to Be.