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We carry out ab initio density functional theory calculations to study manipulation of electronic structures of self-assembled molecular nanostructures on metal surfaces by investigating the geometric and electronic properties of glycine molecules on Cu(100).It is shown that a glycine monolayer on Cu(100)forms a two-dimensional hydrogen-bonding network between the carboxyl and amino groups of glycine using a first principles atomistic calculation on the basis of a recently found structure.This network includes at least two hydrogen-bonding chains oriented roughly perpendicular to each other.Through molecule-metal electronic hybridization,these two chains selectively hybridized with the two isotropic degenerate Cu(100)surface states,leading to two anisotropic quasi-one-dimensional surface states.Electrons occupying these two states can near-freely move from a molecule to its adjacent molecules directly through the intermolecular hydrogen bonds,rather than mediated by the substrate.This results in the experimentally observed anisotropic free-electron-like behavior.Our results suggest that hydrogen-bonding chains are likely candidates for charge conductors.