Images of scanning tunneling microscopy on the Si(001)-p(2 x 2) reconstructed surface

We have investigated in detail the dependence of scanning tunneling microscopy (STM) images of the Si(001)-p(2 x 2) surface on bias and tip-sample distance, based on first-principles molecular-dynamics simulations. STM images on the terrace of the Si(001)-p(2 x 2) surface are found to be similar to those at the S-A-step edges of the Si(001) surface. The present theoretical calculations predict that the STM images strongly depend on the sample bias and tip-sample separations, and that the pi and pi* surface states contribute to the changes of the STM corrugation images.