Динамический потенциал взаимодействия атомов азота с поверхностью кристалла алюминия

Specific features of the angular distributions of accelerated neutral nitrogen atoms at the grazing angles of incidence on the Al(001) crystal surface have been investigated by the computer simulation method. The N–Al pair interaction potential is approximated by the three-parameter Morse potential with the energydependent coefficients. The angular distributions of scattered atoms have been simulated taking into account the interaction between atoms and several atomic layers in the lattice and the atomic displacement during thermal oscillations. The parameters of the pair potential of accelerated neutral nitrogen atoms in the energy range from 10 to 70 keV have been determined according to the best agreement between the calculated dependence of the rainbow scattering angle on the energy of particles incident on the crystal surface and the available experimental data.

О вычислении температуры Дебая и температуры фазового перехода кристалл-жидкость для бинарного сплава замещения

A method of estimating the interatomic pair interaction potential parameters for a binary substitution alloy with consideration for the deviation of its lattice parameter from the Vegard law is proposed. This method is used as a basis to calculate the Debye temperature and Grüneisen parameters of a SiGe alloy. It is shown that all these function nonlinearly variate with a change in the germanium concentration. Based on this technique and Lindemann's melting criterion, a method for calculating the liquidus and solidus temperatures of a disordered substitution alloy is proposed. The method is tested on the SiGe alloy and demonstrates good agreement with experimental data. It is shown that when the size of a nanocrystal of a solid substitution solution decreases, the difference between the liquidus and solidus temperatures decreases the more, the more noticeably the nanocrystal shape is deflected from the most energetically optimal shape.

THE VLASOV CONTINUUM LIMIT FOR THE CLASSICAL MICROCANONICAL ENSEMBLE

For classical Hamiltonian N-body systems with mildly regular pair interaction potential (in particular, [Formula: see text] integrability is required), it is shown that when N → ∞ in a fixed bounded domain Λ ⊂ ℝ3, with energy [Formula: see text] scaling as [Formula: see text], then Boltzmann's ergodic ensemble entropy [Formula: see text] has the asymptotic expansion SΛ(N,N2ε) = - N ln N + sΛ(ε) N + o(N). Here, the N ln N term is combinatorial in origin and independent of the rescaled Hamiltonian, while sΛ(ε) is the system-specific Boltzmann entropy per particle, i.e. –sΛ(ε) is the minimum of Boltzmann's H function for a perfect gas of energy ε subjected to a combination of externally and self-generated fields. It is also shown that any limit point of the n-point marginal ensemble measures is a linear convex superposition of n-fold products of the H-function-minimizing one-point functions. The proofs are direct, in the sense that (a) the map [Formula: see text] is studied rather than its inverse [Formula: see text]; (b) no regularization of the microcanonical measure [Formula: see text] is invoked, and (c) no detour via the canonical ensemble. The proofs hold irrespective of whether microcanonical and canonical ensembles are equivalent or not.