ON THE INTERACTION BETWEEN STEPS IN VICINAL FCC SURFACES .1. STEPS ALONG (001)

Atomistic computer simulations are used to study the zero-temperature interaction between steps in vicinal free fcc surfaces in order to test the continuum-elastic theory of Marchenko and Parshin (MP). Two different types of surface steps, both parallel to [001] but situated, respectively, on the (100) and (110) planes, are investigated using two qualitatively different interatomic potentials, one of the embedded-atom-method type and the other the Lennard-Jones potential. In agreement with the MP theory, for the largest step separations delta the energy due to the step-step repulsion is found to decrease as delta-2, with a strength given by the surface-stess tensor and the elastic moduli of the material. Surprisingly, for both potentials and for both types of steps the delta-2 power law appears to be obeyed even for the smallest step separations, albeit with a 2-3 times smaller interaction strength. The relationship of our simulation results with a nearest-neighbor broken-bond model is also explored.