Interatomic potential for uranium in a wide range of pressures and temperatures

Abstract

Using the force-matching method we develop an interatomic potential that allows us to study the structure and properties of α-U, γ-U and liquid uranium. The potential is fitted to the forces, energies and stresses obtained from ab initio calculations. The model gives a good comparison with the experimental and ab initio data for the lattice constants of α-U and γ-U, the elastic constants, the room-temperature isotherm, the normal density isochore, the bond-angle distribution functions and the vacancy formation energies. The calculated melting line of uranium at pressures up to 80 GPa and the temperature of the α-γ transition at 3 GPa agree well with the experimental phase diagram of uranium.

Thermodynamic properties and phase transitions of γ and liquid uranium: QMD and classical MD modeling

“…As we see the data from Fugure 4 the CMD melting curves at the pressures lower than 100 GPa are close to the results of experiment and similar to calculations [4] employing the coexistence method. It is worth noting that not only the points but the slopes of interpolated curves for experimental and calculated with new EAM data are in good agreement.…”

“…In the case of CMD calculations, embedded atom method (EAM) [8] or modified EAM [18] are used to develop interatomic potential based on ab initio calculated data. Considering solid-liquid transition, Smirnova et al [4] have found that the obtained melting curve of γ uranium is close to the DAC experimental data, but only up to 50 GPa.…”

“…Standard EAM [8] potential form was used as it has proved its usability for describing various phases of uranium [4]. The latter EAM potential (hereafter denoted as EAM-2012) was also used in order to provide a direct comparison of the data from molecular dynamics simulations.…”

“…To this date both classical (CMD) [2,3,4,5] and quantum (QMD) [6,7] molecular dynamics have been used for investigation of uranium thermophysical properties. Although first-principles calculations give more accurate results, their immense computational cost makes the CMD approach more preferable for a study of phase diagrams of the actinides.…”

The New Molecular Dynamics Approach to Study Radiation Processes

“…Атомні маси умовно дорівнюють А1 = 240, А2 = 150, А3 = 28. Значення параметрів потенціалу для взаємодії атомів з вказаними атомами взяті з [10][11][12][13]. Параметри різнорідних атомів були визначені як середні для кожної пари атомів:…”