What is it about?
We use molecular dynamics simulations to model density and viscosity of alkanes. To improve the previous simulation methods, we develop an algorithm that automatically selects where and for how long to perform the simulations, and correct systematic errors in density simulation results.
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Why is it important?
The work presented in the manuscripts resolves two major issues with non-equilibrium molecular dynamics simulations. First, it corrects systematic errors in density simulations, allowing accurate initial conditions for viscosity simulations. Second, the sampling algorithm automatically selects the a set of good shear rates at which to perform the simulations, resulting in a more accurate and systematic simulation method. The algorithmic nature of the sampling algorithm means non-equilibrium dynamics simulations can now be performed in high-throughput screening.
Read the Original
This page is a summary of: Enhancing NEMD with automatic shear rate sampling to model viscosity and correction of systematic errors in modeling density: Application to linear and light branched alkanes, The Journal of Chemical Physics, July 2020, American Institute of Physics, DOI: 10.1063/5.0004377.
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Molecular dynamics density and viscosity simulations of alkanes
We use molecular dynamics to study liquid density of small branched alkanes and kinematic viscosity of linear alkanes. The density models compare well to experimental values, with an average absolute deviation of 3.38 g/l. We run non-equilibrium molecular dynamics simulations for viscosity to explore its shear rate profile, which is used to extrapolate Newtonian viscosity. We develop a new method to systematically identify the range of shear rates at which the simulations are performed. We compare our models of linear alkanes as a function of temperature and pressure with experimental values, obtaining an average percent error of -1.1%.
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