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Variable pseudo-particle modeling for molecular dynamics simulation
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DOI：10.1016/j.cjche.2025.10.015.png)
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Abstract
En 中文
Hard sphere (HS) models are efficient for molecular dynamics simulation of dilute gases, but exhibit limitations for dense and real gases due to its oversimplification of molecular interactions. To improve simulation accuracy for real gases, the variable hard sphere (VHS) model has been proposed. However, similar to the HS model, VHS is difficult to parallelize in computing due to its inherent serial algorithm. The pseudo-particle modeling (PPM), based on a modified HS model, can circumvent this difficulty to some extent and, when further coupled with HS, can achieve almost linear scalability at large-scales, but it is still difficult to accurately simulate real gases. In this work, a variable-diameter model based on PPM (VPPM) was proposed, in which the collision diameter is dynamically determined by the timestep and relative velocity of colliding particle pairs. Through systematic investigation of gas system properties including the mean free path, compressibility factor, and self-diffusion coefficient, the VPPM simulation shows excellent agreement with the VHS results, confirming both the model’s effectiveness and successful coupling of VHS and VPPM. Furthermore, the viscosity coefficients of three-dimensional real gases obtained by VPPM in the temperature range of 300–2000 K are consistent with experimental data, with a maximum relative deviation of only 3.7%, significantly outperforming conventional PPM (48% deviation) and Chapman–Enskog theory (35% deviation). It demonstrates that VPPM is highly suitable for accurate and large-scale parallel simulations of real gases, particularly in high temperature-gradient systems such as gas–solid catalytic reaction, gas diffusion, adsorption and separation in chemical engineering, and aerospace applications, especially under significant temperature gradients.
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