Mechanical instability and nucleation in a Lennard–Jones fcc crystal at limiting stretching

Highlights: • Mechanism of phase decay of a Lennard–Jones crystal has been investigated. • Calculation of the density dependence of elastic moduli. • Boundary of the crystal stability has been determined. The method of molecular dynamics simulation has been used to investigate the mechanism of phase decay of a Lennard–Jones fcc crystal close to the boundary of 'ideal strength'. The attainability of states where the isothermal bulk modulus K_T = ρ(∂p/∂ρ)_T = 0 and K_T < 0 has been demonstrated at negative pressures. It has been shown that the decay of the crystal phase proceeds by different activation mechanisms: (i) by the formation of voids at temperatures below that of the endpoint of the melting line and (ii) by liquid-phase critical nuclei formation above this temperature.