Bonding in the homologous series CsAu, CsAg, and CsCu studied at the 4-component density functional theory and coupled cluster levels

The effects of relativity, electron correlation and, in the case of CsAu, the lanthanide contraction on the bonding in the three intermetallic compounds CsAu, CsAg, and CsCu using both wave function methods and density functional theory were investigated. Although only Csau were observed experimentally, all three compounds were predicted to exist both on the relativistic and nonrelativistic levels of theory with bond energies above 1 eV. Thus, there was a high degree of electron transfer from the cesium 6s orbital to the ns orbital of the noble metal.