  The Newtonian viscosity of 2,2,4-trimethylhexane at 293K is determined at
pressures from 0.1MPa to 1000MPa. Non-equilibrium molecular dynamics
simulations are performed using AIREBO-M, an all-atom potential for
hydrocarbons especially parameterized for high pressures. The steady-state
shear stress and viscosity are determined from simple shear simulations at
rates between $10^7$ and $5\cdot 10^9\ \textrm{s}^{-1}$. At low pressures,
simulation rates are low enough to reach the Newtonian regime. At high
pressures, results are extrapolated to the Newtonian limit by fitting
rate-dependent viscosities to Eyring theory. The resulting pressure dependent
viscosity is typical of small molecules and fits to a common model are
discussed.
