Contributions of vibrational dynamics to the local and excess thermodynamic properties of Cu3Au surfaces

In a comparative study of the local and excess thermodynamic properties of ordered (100), (110), and (111) surfaces of Cu,An using interaction potenti als from the embedded atom method, and a real space Green's function method for the calculation of the local vibrational density of states, we find su rface effects to be most pronounced on (110). The enhancement of the low fr equency modes resulting from the softening of intralayer force constants ca uses a remarkable lowering of the vibrational free energy on (110). On Cu3A u(100) the stiffening of interlayer force constants leads to the appearance of modes above the bulk band that reduce the effect of the enhancement of low frequency modes. Atoms on all three surfaces display characteristics th at are distinct from those in the bulk.