Charge density waves, spin density waves, and Peierls distortions in one-dimensional metals. I. Hartree-Fock studies of Cu, Ag, Au, Li, and Na

Ab initio calculations indicate that each of the one-dimensional elemental metals composed of Cu, Ag, Au, Li, and Na is stable with respect to the Peierls distortion if spin polarization is allowed [unrestricted Hartree-Fock (UHF)], leading to a spin density wave. Disallowing spin polarization [restricted Hartree-Fock (HF)] leads to a half-filled energy band, Peierls instability, and a charge density wave. For each case, the UHF wave function leads to an antiferromagnetic (nonmetallic) ground state, with a spin density wave resulting from electron correlation effects, consistent with the Mott-Hubbard low-density antiferromagnetic insulator. The UHF antiferromagnetic (nonmetallic) ground states have large cohesive energies resulting from two-center one-electron bonds (similar to the one-electron bonds of the diatomic molecular cations).