Ab initio calculations and dynamical properties of the Se:InP(1 1 0) and Te:InP(1 1 0)

We present results of ab initio theoretical investigations of the structural and dynamical properties of the Se:InP(1 1 0) and Te:InP(1 1 0) surfaces, by employing the plane wave pseudopotential method, the local density approximation of the density functional theory, and a linear response scheme. For both adsorbates we have used the so-called exchange geometry (the chalcogen atoms replacing P in the top two atomic layers). A detailed discussion is provided of the relaxed surface geometry and phonon dispersion curves along two principal symmetry directions. It is found that the adsorption of Se (or Te) atoms on InP(1 1 0) leads to phonon modes in the acoustic-optical gap region for bulk InP. The characteristic atomic displacement patterns of selected phonon modes on these surfaces have been compared and contrasted with those on the clean InP(1 1 0) surface.