Pairing, π-bonding, and the role of nonlocality in a dense lithium monolayer

Results of self-consistent ab initio all-electron calculations of a lithium monolayer are presented. Upon increase in mean density, the electronic structure of the monolayer is found to deviate significantly from nearly free electronlike behavior: instead of growing with compression, the width of lowest subband actually diminishes. The resulting band structure exhibits a rr-bonding character, and it is found that this feature cannot be modeled with a local pseudopotential. Similar to the case in three dimensions, the monatomic monolayer is also found to be unstable to pairing at r(s) = 1.96.