Structural and dynamical properties of iridium surfaces: First principles and molecular dynamics investigations

The structural and dynamical properties of Ir(l 00) clean surface are investigated in the temperature range 100-1100 K. We performed molecular dynamics (MD) simulations using the interaction potential energies obtained from the density-functional theory (DFT) and plane-wave pseudopotential (PWPP) method. The obtained contraction of the first interlayer distance, d(12), decreases from -4.94% at 100 K to -4.84% at 1100 K. This decrease deviates by 11.8% at 100 K to 13.6% at 1100 K, from that at OK (-5.6%). The expansion of the second interlayer distance, d(23), however increases from 0.89% at 100 K to 1% at 1100K, causing a deviation that ranges from -11% to 0% from that at 0 K (M). The deviation of the calculated surface vibrational frequencies and surface relaxations over the entire range of temperatures (100-1100 K) is rather modest as a result of small anharmonic effects of the surface. (C) 2008 Published by Elsevier B.V.