Equation ͑3͒contained a typographical error and should be replaced by the following equation:The published results were calculated using the correct equation.

We present a comparative study of the local and excess vibrational thermodynamic functions for the ͑511͒, ͑211͒, and ͑331͒ surfaces of Ag and Cu, in the harmonic approximation, employing interaction potentials based on the embedded atom method. Related thermodynamic functions of the corresponding ͑100͒ and ͑111͒ surfaces are also examined. For these surfaces, local contributions to the vibrational free energy for atoms in layers down to the fifth are found to deviate from that of the atoms in the bulk, as a result of complex multilayer relaxations. These contributions show a linear dependence on temperature, beyond 200 K, and a correlation with the local coordination but without a simple relationship. The vibrational contribution to the step excess free energy for vicinals of ͑111͒ is found to be significant.

A molecular dynamics study of the thermodynamic properties of liquid Ni using the Voter and Chen version of the embedded atom model

We have calculated the vibrational dynamics and thermodynamics for Cu adatom hopping on terraces and near step edges on Cu(100) and Cu(110), using the embedded atom method for the interatomic potential. The local vibrational densities of states were calculated using real space Green's function formalism and the thermodynamical functions were evaluated in the harmonic approximation. The calculated diffusion energy barriers for six specific local environments on Cu(100) agree well with experimental and previous theoretical results.Contribution of vibrational entropy to the change in the free energy of the system as the adatom moves from the equilibrium configuration (hollow site) to the saddle point, is found to be as much as 55meV (144 meV) at 300K (600K). The prefactors for all 13 cases are found to be of the order of 10 -3 cm 2 /s, almost independent of temperature, and the respective activation energy barriers.

We have developed a semi-empirical and many-body type model potential using a modified charge density profile for Cu-Ni alloys based on the embedded-atom method (EAM) formalism with an improved optimization technique. The potential is determined by fitting to experimental and first-principles data for Cu, Ni and Cu-Ni binary compounds, such as lattice constants, cohesive energies, bulk modulus, elastic constants, diatomic bond lengths and bond energies. The generated potentials were tested by computing a variety of properties of pure elements and the alloy of Cu, Ni: the melting points, alloy mixing enthalpy, lattice specific heat, equilibrium lattice structures, vacancy formation and interstitial formation energies, and various diffusion barriers on the (100) and (111) surfaces of Cu and Ni.

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We present here a summary of the calculated structural, dynamical and thermodynamical properties of a number of vicinal surfaces of fcc metals with the aim of identifying trends in their characteristics. In general, multilayer relaxations indicate a contraction in the bonds between surface atoms except for that of the least undercoordinated surface atom (‘corner’) whose bond length with the nearest neighbour bulk atom displays an impressive expansion. Electronic structure calculations show a rearrangement of charge densities near the steps and the layer resolved density of states highlights the characteristics of the undercoordinated atoms. The frequencies of localized vibrational modes on stepped surfaces point to both softening and stiffening of specific force constants, which lead to enhancement of modes in both the lower and higher ends of the frequency spectrum in the vibrational densities of states. Contributions to the surface vibrational entropy from undercoordinated atoms are found to depend strongly on their atomic coordination and play an important role in determining the step excess free energy for certain step geometries. Comparisons of results are made with available experimental data.

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