Lattice-gas Hamiltonian revisited: O-Pd(100)

摘要

The methodology of deriving an adatom lattice-gas Hamiltonian (LGH) fromfirst principles (FP) calculations is revisited. Such LGH expansions computelateral interactions by solving a set of linear equations describing regularadatom configurations and their FP energies. The basic assumption of truncatinginteraction terms beyond fifth nearest neighbors does not hold when adatomsshow longer range interactions, e.g. substrate mediated elastic interactions.O-Pd(100) as a popular reference is used to propose a long range elasticinteraction alternative including trio- and quattro terms with just 3parameters fitted to FP calculations. Adatom pair distributions are derived upto half coverage using an adapted Boltzmann distribution and compared with LEEDdata. A scaling scheme for varying temperatures is provided. Adatom three-bodydistributions are used to analyze adatom near order. Long range order ofadatoms is not found with the elastic model. The assumptions made are discussedand ways to further verify and apply the model are outlined.