Ab initio Calculation of Structure and Dynamics of Semiconductor Surfaces with Adatoms
Structure and dynamics of adatom induced Si(111)-(1 1) and
Si(111)-( )R3 surfaces have been studied
by means of first principles methods. For the Arsenic and Hydrogen
covered 1 1 surfaces and for the Gallium and Boron covered
surfaces, the relaxation is determined
by minimizing the total energy within the local density
the full phonon dispersions are calculated using
the density functional perturbation theory (DFPT).
The phonons of the Aluminum and Indium covered surfaces are
studied within a simple mass approximation. All results for the
surface localized modes are in good agreement with the experimental
The observed anomalously large amplitudes of Ga vibrations at elevated
temperatures  are compared to the
mean square displacements calculated
within the harmonic approximation.
Anharmonic effects are scrutinized for the adsorbate vibrations of the Si(111):H-(1 1) surface. The influence of the zero-point motion and the substrate modes on the Si-H bond stretching mode at the -point are studied via cubic and quartic anharmonic coupling coefficients which are obtained by combining DFPT and the frozen phonon method. The calculation of the temperature dependent line shift in lowest order perturbation theory includes also the surface thermal expansion. The broadening of the Si-H stretch vibration is obtained within higher order anharmonic perturbation theory using an on-site potential approximation. The results compare well with all available experimental data.
 R.E. Martinez, E. Fontes, J.A. Golovchenko, and J.R. Patel,
Phys. Rev. Lett. 69, 1061 (1992).