Development of a Polarizable Interatomic Potential for Molten Lithium, Sodium, and Potassium Nitrate

Abstract

A polarizable interatomic potential is developed for atomistic simulations of molten MNO3 (M = Li, Na, K) salts. The potential is parametrized using a force matching method relying on the adjustment of parameters such that density functional theory generated forces, stress tensors, and dipole moments are reproduced. Simulations conducted using the new potential are used to estimate physical parameters of the melt, which are then compared with available experimental results. The average calculated densities of NaNO3 and KNO3 are within 2% of the experimental value within the temperature range studied, while that of LiNO3 is within 3%. Thermal conductivities and viscosities are estimated using equilibrium calculations and the Green–Kubo method. The thermal conductivity values of NaNO3 and KNO3 are found to match well with experimental data, while that of LiNO3 is approximately 20% larger than experimentally determined values throughout the temperature ranges simulated. The calculated viscosities are also in good agreement with experimentally determined values. The (Na x K1–x )­NO3 mixture is also investigated, with densities, thermal conductivities, and viscosities determined and compared with experimentally determined values where available. Additionally, radial and angular distribution function data is presented for all salts, revealing details of the atom-level structures present in the melts. We have found that the new interatomic potential is effective for atom scale modeling of the physical properties of molten nitrate salts.

Machine Learning Accelerates Molten Salt Simulations: Thermal Conductivity of MgCl2‐NaCl Eutectic

“…There has been a long-standing interest in developing accurate interatomic potentials for molten salt (MS) systems, although this can be very time-consuming and requires considerable expertise. [1][2][3][4] This is partly due to their current and potential applications, including electrolysis-based metal production, molten salt reactors, concentrated solar power plants, etc. [5][6][7] A fundamental understanding of thermophysical properties is required for developing high-performance MS materials.…”

Machine-Learning-Driven Simulations on Microstructure and Thermophysical Properties of MgCl2–KCl Eutectic

“…As an alternative to the experiment, molecular dynamics (MD) simulations have been widely used in studies of molten salt systems, which can enhance our understanding of molten salt systems at an atomic level . So far, a considerable amount of research has been conducted on nitrate/nitrite, , carbonate, , and alkali chloride salts ,− using empirical potential. Conversely, there has been less research on alkaline earth chloride salts .…”

First-principles study on the structural, elastic, electronic, optical and thermophysical properties of NaNO3 and K-doped NaNO3

“…As mentioned in table 4, the value of NaNO 3 approaching 0.25 suggests the existence of both central forces and ionic bonds within the compound. When the Poisson's ratio (ν) exceeds 0.26, the material is considered ductile, whereas if ν falls below 0.26, the material is categorized as brittle [22]. So, it can be deduced that the compound NaNO 3 displays characteristics indicative of brittle behavior, whereas K-doped NaNO 3 demonstrates attributes associated with ductile For NaNO 3 the current derived values are in good agreement with those published in the literature, Only the B r value is changed by 8.6%.…”

“…KNO 3 and NaNO 3 are both key components in the formulation of pyrotechnic compositions and explosives. Maxwell et al also employed molecular dynamics (MD) simulations to investigate the properties of (Na x K 1-x )NO 3 , revealing insightful findings regarding the physical characteristics of this system [22]. By studying their combination, we can develop safer and more efficient pyrotechnic mixtures with tailored properties.…”