Scanning-tunneling-microscopy and spectroscopy simulation of the GaAs(110) surface

We have generated, using an ab initio pseudopotential method and the Bardeen transfer Hamiltonian approximation, scanning-tunneling-microscopy images and scanning-tunneling-spectroscopy spectra of the GaAs (110) surface. The surface was fully relaxed and a cluster of four Al atoms was used to represent the tip. We investigate the effect of different tip-surface bias voltages on the scanning-tunneling-microscopy images and ompare them to experimental results. In particular, the effectiveness of using the images to determine the buckling angle of the surface bond is discussed. For the scanning-tunneling-spectroscopy spectra, different lateral tip positions were utilized and various features associated with surface states were identified, which we also compare with experiment.