Nitrogen and sulfur atom adsorption on flat and stepped gold surfaces are examined by density functional theory. With detailed investigation of adatom location on the (111), (100), and (211) gold surfaces, nitrogen and sulfur atom adsorption are compared with reference to previous work on the oxygen/gold system. Sulfur adsorbed most strongly, followed by oxygen and nitrogen. The results demonstrate the preference for 3-fold over 2-fold and single-fold adatom coordination as well as the role of low coordinated gold surface atoms in increasing the adsorption energy for nitrogen, sulfur, and oxygen atoms. Pseudopotential curves, calculated adsorption energy as a function of surface position, and nudged-elastic band calculations explored adatom diffusion along the surface. The results indicated limited diffusion on the (111) and (211) surfaces. On the other hand, while nitrogen and sulfur atoms remained localized on the (100) surface, oxygen atoms showed facile diffusion. These results provide a reference for the interaction of nitrogen, sulfur, and oxygen adatoms with gold nanoparticles that project faces similar to the surfaces studied here.

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The properties of a new method of performing molecular dynamic simulations of complex chemical processes are presented. The method is formulated to give a time-dependent, multilevel representation of the total potential that is derived from spatially resolved quantum mechanical regions. An illustrative simulation is performed on a 110 atom system to demonstrate the continuity and energy conserving properties of the method. The effect of a discontinuous total potential upon the kinetic energy of the system is examined. The discontinuities in the magnitude of atomic force vectors due to changing the electronic structure during the simulation are examined as well as the effect that these discontinuities have upon the atomic kinetic energies. The method, while not conserving total energy, does yield canonical (NVT) simulations. The time reversibility property of the simulation with an extremely discontinuous total potential is discussed. The computational scaling associated with the formation of the spatially resolved, time-dependent groups is also investigated.