Advantages of the Rayleigh-Lowe-Andersen thermostat in soft sphere molecular dynamics simulations.

The Rayleigh-Lowe-Andersen thermostat is a momentum-conserving, Galilean-invariant analogue of the Andersen thermostat, like the original (Maxwellian) Lowe-Andersen thermostat. However, the Rayleigh-Lowe-Andersen thermostat remains local even if the fluid density becomes low. By using a minimized thermostat interaction radius we show with a molecular dynamics simulation that the Rayleigh-Lowe-Andersen thermostat affects the natural dynamics of a low-density Lennard-Jones fluid in a minimal fashion. We also show that it is no longer necessary to consider a separate simulation just to determine the optimal value of the thermostat interaction radius. Instead, this value is computed directly during the main simulation run. Because the Rayleigh-Lowe-Andersen thermostat can be combined with the velocity Verlet integration scheme, we expect a widespread applicability of the thermal mechanism presented here.

Erratum to: A modified Lowe-Andersen thermostat for a hard sphere fluid.

There are two small errors at the beginning of sect. 2 which have been corrected in the present erratum.

A modified Lowe-Andersen thermostat for a hard sphere fluid.

In order to model the thermal interaction between two hard sphere particles, we propose a small modification of the Lowe-Andersen thermostat, a well-known numerical thermostat that acts on selected pairs of particles. The simulation procedure presented here is local, easy to implement and computationally inexpensive while perturbing the natural dynamics of the system in a minimal fashion.

Cosine law for the atomically rough nanopore: Modeling lattice vibrations with a modified Lowe-Andersen thermostat.

This work proposes a simulation technique that can be used to compute the thermal interaction between a rarefied gas and an atomically rough nanopore. A standard pore geometry, the slit pore, is used to derive the correct version of the cosine law in case the wall consists out of individual atoms. Having the correct cosine law drastically reduces the computational cost of calculating the gas-wall pair interaction in the rarefied gas regime since it is no longer necessary to consider a fully flexible crystal lattice. By considering only a small modification of the Lowe-Andersen thermostat, a well-known simulation technique that uses diffusive gas-heatbath collisions, we show how it can be used to incorporate lattice flexibility even if the wall is modeled as a rigid lattice.

Drift velocity of a Smoluchowski gas: a numerical demonstration of the fluctuation-dissipation theorem.

This Brief Report shows that the Smoluchowski thermostat, a stochastic boundary condition used to mimic a diffusive gas-wall collision, produces the correct stationary nonequilibrium states. The stationary states are generated by placing an ideal gas coupled to a Smoluchowski thermostat in a constant external field. It is shown by simple numerical simulations that the resulting drift velocity is compatible with the definition of the gas particle mobility, satisfying the well-known fluctuation-dissipation theorem. As an interesting application, it is shown that species that are chemically identical but differ in surface momentum accommodation can be separated effectively in the Knudsen regime.

Smoluchowski thermostat: a realistic introduction of the tangential momentum accommodation coefficient.

This work presents a simulation technique that can be used to compute the thermal interaction between a gas and a cylindrically shaped wall. The method is computationally simple and is based on the Maxwell-Smoluchowski thermal wall scenario often used for the slit pore geometry. A geometric argument is used to find the corresponding thermalization mechanism for the cylindrical confinement. The algorithm serves as a thermostat, which enables one to perform constant-temperature simulations. By means of simple numerical simulations, Smoluchowski's expression for self-diffusivity D s is then recovered in reduced units. The tangential momentum accommodation coefficient is interpreted as a coupling constant for the thermostat similar to the one used for the ordinary Andersen thermostat but applied locally onto the boundary crossing particles.