Structure and melting of Morse solids

Isothermal-isobaric ensemble Monte Carlo simulations are used to study the melting of Mor se solids. At a given pressure, the temperature at which the solid ceases to be metastable and also the fractional changes in density a nd potential energy increase with decreasing range of the Morse pair potent ial. The structural properties of the liquid and solid phases vary signific antly with the range. The longer range, softer potentials are associated wi th increased densities and cohesive energies in both the solid and liquid p hases. The extent of local disorder associated with lattice sites in the so lid phase, as measured by the Lindemann and bond orientational order parame ters, increases with increasing range of the pair potential.