temperature in steps of $\Delta T=0.05$. As before we equilibrate at each temperature for $10^4$ time steps and then measure quantities for an additional $10^6$ time steps.

We have also done some density sweeps in which we fix the temperature (T=1.0) and systematically change the density. The glass transition occurs as we increase the density. Colloidal experiments often study the glass transition as a function of density. We start each run at a low density ($\rho=0.4$) and increase the density in steps of $\Delta\rho=0.025$. At each density we equilibrate for $10^4$ md steps and then measure the quantities of interest for $N_{\tau}$ additional md steps.

The glass transition occurs either as the temperature is lowered or as the density is raised. It is worth noting that temperature and density can be combined into a dimensionless parameter $\Gamma$ [@Barrat90]: $$\label{eq:gamma_eff}
\Gamma =\rho\sigma_{eff}^3/T^{\frac{1}{4}}\qquad
\sigma_{eff}^3=\sum_{\alpha\beta}n_{\alpha}n_{\beta}
\sigma_{\alpha\beta}^3$$ where $\sigma_{eff}$ represents an effective diameter for particles in the mixture. The concentration of each type of particle is given by $n_A=N_A/N$ and $n_B=1-n_A$. For our simulations $n_A=n_B=0.5$. $\Gamma$ is the relevant parameter when the particles spend most of their time sampling a nonzero interparticle potential, i.e., for $\rho^{-1/3}<\sigma_{eff}$. Thus $\Gamma$ is particularly useful for interparticle interactions 