Bi

Abstract: A semi-empirical interatomic potential for the post-transition metal, bismuth, is developed based on the second nearest-neighbor modified embedded-atom method (MEAM). The potential reproduces a range of physical properties, such as the lattice constant, cohesive energy, elastic constants, vacancy formation energy, surface energy, and the melting point of pure bismuth. The calculations are done for the rhombohedral ground state of Bi. The results show good agreement with density functional theory and experimental data. The developed MEAM potential for bismuth is useful for material and mechanical behavior studies of the pure material at different conditions and sets the stage for the development of interatomic potentials for bismuth alloys or other bismuth compounds.

Abstract: The embedded atom model (EAM) potentials of liquid gallium, lead, and bismuth calculated by the author using the Schommers algorithm were refined and written in a unified analytic form more convenient for applications. Pair contributions to EAM potentials are described by piecewise continuous functions. The form of EAM potentials admits the transition to a high-density state characteristic of shock compression. Series of models of these liquid metals were constructed by the molecular dynamics method at temperatures up to 1500 (Zn), 3000 (Ga, Pb), and 1800 K (Bi). For all the metals, close agreement with experiment was obtained over the whole temperature range for density, structure, bulk compression modulus, and self-diffusion coefficient. The standard deviations of model pair correlation functions (PCF) from the diffraction PCFs of gallium and lead were on the order of 0.01. As distinct from alkali metals, the calculated energy of gallium and lead models was close to actual energy over the whole temperature range, and excess electronic heat conductivity was almost unobservable. With bismuth, agreement with experiment for energy and structural characteristics was noticeably worse, which shows that the embedded atom model is less applicable to bismuth.