A MOLECULAR-DYNAMICS STUDY OF LIQUID-SOLID TRANSITIONS .2. SYSTEM-SIZE AND PRESSURE EFFECTS

A molecular-dynamics (MD) calculation of the transitions between Na-li quid and Na-solid (crystal or glass) is performed for (a) different sy stem sizes, (b) different initial conditions of the prepared Na liquid s, and (c) low and high pressures. In addition, the system-size and pr essure effects on the transitions of interest are demonstrated. It app ears that (i) the system-size effect is much more significant for the transitions between metallic liquid and crystal than for the metallic glass transitions, lending support to the validity of the frozen model of glasses, (ii) the system-size effect decreases rapidly as the numb er of atoms, n, increases from 1500 and becomes negligible as n approa ches 3500 in a realistic constant-pressure MD calculation of the metal lic liquid-crystal transition, (iii) high pressure significantly affec ts the time of formation of critically sized nuclei and crystal growth through the change of volume in the crystallization of a liquid and ( iv) for a system to be a good glass-former, the atoms in this system m ust have a large probability of forming non-crystalline-like local ord ered units.