Charge density waves, spin density waves, and Peierls distortions in one-dimensional metals. 2. Generalized valence bond studies of Cu, Ag, Au, Li, and Na

Ab initio generalized valence bond (GVB) calculations indicate that the one-dimensional elemental metals composed of Cu, Ag, Au, Li, and Na are each stable with respect to the Peierls distortion. This results because of the strong cohesion resulting from two-center one-electron bonds (as opposed to two-center two-electron bonds). Hence, the Peierls distortion stretching and compressing alternate one-electron bonds is unfavorable. For each system, GVB leads to a singlet (low-spin) ground state having fully symmetrical charge and spin densities (no charge density wave and no spin density wave). Some of these GVB results are in complete disagreement with results calculated with less sophisticated wave functions such as restricted Hartree-Fock and unrestricted Hartree-Fock. Comparison of the GVB and Hartree-Fock wave functions reveals the origins of these errors in the Hartree-Fock descriptions.