Molecular dynamics calculation of properties of liquid gallium and tin under shock compression

Resumo

The embedded atom model (EAM) potentials are proposed, enabling the description of liquid gallium and tin under conditions typical to shock compression. The potentials reported earlier to describe metals under pressures close to normal and the experimental data on shock compression are used. Series of models are constructed 2000 or 2048 atoms in size in a basic cube at compression ratios Z up to 0.5 of the initial volume under pressures up to 385 GPa and temperatures up to 32000 K. These potentials give a satisfactory description of liquid gallium and tin under shock compression. The thermodynamic properties of the metals at compression ratios up to 0.5 and temperatures up to 20000 K are calculated and given in tabular form. In the case of gallium, a small compression of models with normal density decreases the total energy at 300, 500, 15000, and 20000 K, and, for tin, this effect is observed only at 20000 K. The energy and pressure of the FCC metal models are markedly lower than those of noncrystalline models. The cold pressure for the states at temperatures between 0 and 298 K is evaluated. The EAM potential of tin leads to a lowering of the cold pressure of an FCC lattice with respect to the amorphous phase at Z < 0.75.