IONICITY OF K-CHEMISORBED ON A CU SURFACE

We have determined that K chemisorbed on a Cu(100) surface is highly ionic K+ for a low coverage of K. Our results are based on Hartree-Fock SCF cluster calculations. Various properties have been analyzed to establish the ionic character of the Cu-K bond. These include: (1) the dipole moment curve as a function of the Cu-K distance; (2) constrained variations of the SCF orbitals to separate polarization effects from charge transfer; and (3) charge density difference plots. A cost/benefit analysis is applied to show that the ionic bond is energetically favorable.