EFFECT OF TIP ATOMIC-STRUCTURE ON SCANNING TUNNELING SPECTROSCOPY

Tunneling conductance in scanning tunneling spectroscopy of graphite is simulated by the first-principles electronic structure calculation. As models of tip, W10[111], W14[110], and Pt10[111] clusters are adopted. Simulated tunneling spectra are influenced by the shape of tip apex and deviate from one obtained by the theory assuming the conductance proportional to the surface local density of states. A broader energy spectrum of tip levels reproduces well the experimental data. © 1990.