MD simulation of a supercooled liquid metal and glasses

Hyon-Jee Lee, Yue Qi, Alejandro Strachan, Tahir Cagin,

William A.Goddard III, and William L. Johnson

Materials and Process Simulation Center (MSC)

Division of Chemistry and Chemical Engineering and

Division of Engineering and Applied Science

Caltech

Abstract:

Using the quantum Sutten Chan many body force field, we carried out molecular dynamics (MD) simulations to describe the transport properties of a supercooled liquid metal alloy near the glass transition temperature, Tg. As a model system we considered the alloy CuxCu*1-x, where x=0.4 and Cu* has an identical force field to Cu, except that it is 13% larger. We find that the temperature dependence of the diffusivity D can be partitioned into three regimes bounded by Tg and a characteristic temperature T1:

We find that the temperature dependence of diffusivity in each regime can be fitted to the Arrhenius form,

D(T) = D0 exp(-QD/kBT).

We find that the activation energy is

Physically, the decrease in QD corresponds to a decreased potential energy barrier in configurational energy landscape.