Showing papers on "Interatomic potential published in 1981"
TL;DR: In this paper, the structure and temperature of rare gas clusters produced during a free jet expansion are studied by electron diffraction, and it is shown that the structure of the clusters depends only on their size, whereas the temperature of clusters is size independent.
53 citations
TL;DR: In this article, the role of attractive forces in determining the static structure factor S(q) for simple liquids was examined and it was shown that the attractive forces ensure that alpha, the coefficient of q2, is negative for most thermodynamic states.
Abstract: Examines the role of attractive forces in determining the static structure factor S(q) for simple liquids. By treating these forces in a random-phase approximation and the repulsive forces in a blip function expansion about a hard-sphere reference system the authors derive explicit results for the coefficients of q2, q3 and q4 in the expansion of c(q), the Fourier transform of the Ornstein-Zernike direct correlation function of a Lennard-Jones liquid, they show that the attractive forces ensure that alpha , the coefficient of q2, is negative for most thermodynamic states. This implies that even near the triple point a simple (argon-like) liquid should exhibit 'residual' Ornstein-Zernike behaviour, i.e. there should be a shallow minimum in S(q) for q approximately=0.25AA-1. The authors find that the short-range correlation length, R=(- alpha rho )1/2 varies weakly with density rho and with temperature. Their calculated value for R at the critical point is in good agreement with results obtained from radiation scattering experiments on Ar and Kr near their critical points. The q3 term is associated with r-6 asymptotic behaviour of the interatomic potential. The authors analysis suggests that it may be possible to detect such a contribution, if it is present in a real liquid, by X-ray or neutron diffraction.
42 citations
TL;DR: In this article, the formation entropy for a vacancy in an Hcp lattice is calculated by assuming a pair interatomic potential which reproduces some Mg properties, and a value of that entropy between 1.5 and $2k$ is obtained at variance with previous experimental findings which favor a very small value.
Abstract: By assuming a pair interatomic potential which reproduces some Mg properties, we calculate the formation entropy for a vacancy in an hcp lattice. A value of that entropy between 1.5 and $2k$ is obtained at variance with previous experimental findings which favor a very small value. By a quasistatic computer-simulation approach the migration energies for the vacancy on different lattice directions are also calculated; two different potentials are used for this calculation. Subsequently migration entropies and diffusivities are evaluated. A good agreement with reported experimental values is obtained. Diffusion in hcp structures is space anisotropic, and the relative influence on this anisotropy of the migration energy with respect to the entropy is discussed.
28 citations
TL;DR: In this paper, a discrete lattice model is used to investigate the interaction of vacancies with a dislocation in the BCC metal, molybdenum, and the formation energies and formation volumes for the vacancy and six interstitial configurations are investigated and the results compared with previous studies for FCC metals.
Abstract: A discrete lattice model is used to investigate the interaction of vacancies with a dislocation in the BCC metal, molybdenum. A new interatomic potential to represent molybdenum has been produced. The formation energies and formation volumes for the vacancy and six interstitial configurations are investigated and the results compared with previous studies for FCC metals. Two edge dislocations with 1/2(111) Burgers vector with either (110) or (112) slip planes have been simulated and the interaction energy with a vacancy at various sites around the core calculated. The results are compared with those from similar studies for iron and with the predictions of continuum elasticity theory.
27 citations
01 Jan 1981
TL;DR: A first-principles interatomic potential for potassium has been used to compute the Peierls stress for a rigid screw dislocation at OK as a detailed function of orientation for uniaxial tension and compression as mentioned in this paper.
Abstract: A first-principles interatomic potential for potassium has been used to compute the Peierls stress for a rigid screw dislocation at OK as a detailed function of orientation for uniaxial tension and compression. The calculated relative orientation dependence is markedly different from that observed in body-centred cubic transition metals, but is in reasonable agreement with experiments performed on potassium. The calculated magnitude of the Peierls stress, however, is uniformly a factor of three too large. Some possible explanations for this discrepancy are discussed.
11 citations
TL;DR: In this article, the interaction energy between a helium atom and a string of beryllium atoms is evaluated by means of a non-empirical ab initio pseudopotential method normally used for molecular calculations.
11 citations
TL;DR: In this article, the authors show that the widely quoted semiclasdcal inversion of the 4 He-4 He total scattering cross section data in the region of the low repulsive wall is inconsistent with both a recent ab initio and a semi-empirical potential representing the helium interatomic forces.
9 citations
TL;DR: In this article, the elastic scattering cross-sections are calculated both in the framework of Lindhard wide-angle extrapolation method and on the basis of an exact solution of the classical equation of motion of a particle in a central-force potential.
Abstract: The elastic scattering cross-sections are calculated both in the framework of Lindhard wide-angle extrapolation method and on the basis of an exact solution of the classical equation of motion of a particle in a central-force potential. Using a direct method for the numerical solution of integro-differential equations governing the ion implantation spatial distribution parameters, the projected ranges, projected and lateral stragglings, and skewnesses are calculated in a wide interval of reduced energies. It is shown that for incident energies e < 0.1 all these parameters are affected by the choice of both the interatomic potential and elastic scattering cross-section approximation.
[Russian Text Ignored].
6 citations
TL;DR: In this paper, simultaneous measurements of the differential electron attachment cross section and the differential elastic scattering cross section have been measured for H(1s) atoms colliding with a caesium vapour target.
Abstract: Simultaneous measurements of the differential electron attachment cross section and the differential elastic scattering cross section have been measured for H(1s) atoms colliding with a caesium vapour target. To interpret the structures seen in all the measured cross sections the authors have calculated semiclassical differential cross sections using the lowest order stationary phase approximation, JWKB phaseshifts and the landau-Zener transition probability. For the inelastic channel leading to H- production the measurements show two types of oscillating features. The Stueckelberg oscillations are due to the interference of scattering from different potentials inside the pseudo-crossing of the covalent and ionic potential curves. Interference due to scattering from the ionic interatomic potential produces a rainbow structure corresponding to a well depth De=1.90+or-0.04 eV at the equilibrium separation of the X1 Sigma state. This well depth is consistent with the attenuated rainbow structure observed on the elastic channel.
5 citations
TL;DR: In this paper, it was suggested that information on the hardness of the repulsive potential in metals may be obtained by examining the long-range part of the liquid structure factor, and it was shown that Ni has a harder core than Ar.
Abstract: It is suggested that information on the hardness of the repulsive potential in metals may be obtained by examining the long-range part of the liquid structure factor. By comparing the measured liquid structure factor of Ni with that of Ar it is shown that Ni has a harder core than Ar.
1 citations
TL;DR: In this article, a technique for the inversion of the scattering incomplete total cross-section was utilized to obtain a numerical evaluation of the interatomic potential for the combinations K + He, K + εNe, K+ εAr, K plus εKr, εXe. The results obtained were employed to recalculate, by means of a nonlinear best fit, the constants appearing in the Brinkman potential.
Abstract: A technique for the inversion of the scattering incomplete total cross-section was utilized to obtain a numerical evaluation of the interatomic potential for the combinations K + He, K + Ne, K + Ar, K + Kr, K + Xe. The results obtained were employed to recalculate, by means of a non-linear best fit, the constants appearing in the Brinkman potential. The new values of these constants were used in the calculation of the sputtering coefficient Ar + Cu in the region 0.5–10 keV. The results are in good agreement with the experimental data.