## 1 Introduction  
Molten chloride salts have been widely used in liquid metal batteries [1; 2; 3], high-temperature heat storage materials, heat transfer mediums [4], and metal electrolytes, owing to their favorable characteristics, such as wide operating temperature range, low vapor pressure, moderate heat capacity, low cost, and high thermal stability [5]. Both the structure and properties of molten chloride salts are hard to measure due to the extreme high-temperature, corrosive, and volatile conditions, needless to consider the accuracy of testing. Fortunately, computer simulation methods have been developed rapidly in recent years, which could give deep insight into the microstructure and the properties of molten salts. The mixtures of molten salts have been investigated intensively in the past years, and the composition dependence of properties has often been the central topic. [PERSON] and [PERSON] [6] firstly studied the internal mobility of molten (Li, Na, K)Cl of its nearly eutectic composition at 773 K, 873 K, and 973 K by molecular dynamics (MD) simulation. Molecular dynamics simulation had been carried out on molten quaternary systems (Li, Na, K, Cs)Cl at 625 K and (Li, Na, K, Cs)F at 727 K to investigate the composition dependence of electrical properties, which was taken as the fundamental study for the pyrochemical reprocessing of spent metallic fuels in molten salts [7]. Later, [PERSON] et al. [8] simulated the electric properties in a temperature range of 800-1100 K for molten ternary mixtures (Li, Na, Cs)Cl. The temperature dependence of Chemla crossing points and the limit of Cs enrichment were discussed. Recently, more attention was paid to the correlation between the structure and properties in liquids. [PERSON] et al. [9] studied the local structure around La\({}^{3+}\) ions in molten LaCl\({}_{3}\) and its mixtures with alkali and alkaline earth chlorides for the electrochemical reprocessing of nuclear fuels. [PERSON] et al. [10] investigated the electrical conductivities of molten LiF-YF\({}_{3}\) and LiF-NaF-ZrF\({}_{4}\) by impedance measurements and MD simulation. They found that conductivity decreases with the addition of MF\({}_{n}\) (M\({}^{n+}\) = Y\({}^{3+}\) or Zr\({}^{4+}\)) due to the formation of MF\({}_{x}^{n-x}\) units. The molecular dynamics simulations on mixtures composed of MCL\({}_{3}\) (where M\({}^{3+}\) is Y\({}^{3+}\), Tb\({}^{3+}\), La\({}^{3+}\), and U\({}^{3+}\)) in (LiCl-KCl)\({}_{\text{eut}}\) were conducted, and the correlation between the viscosity and structure was discussed in depth [11]. [PERSON] et al. [12] investigated a molten ZnCl\({}_{2}\)-NaCl-KCl system by MD, and the interplay between the extent of the network structure, composition, and transport properties (viscosity, thermal conductivity, and diffusion) was characterized. The network modification due to the addition of K ions leads to the formation of non-bridging terminal Cl ions, and leads to a positive temperature dependence of thermal conductivity in these melts, a valuable property for heat transfer fluid design. Most of the work concentrated on complex multi-valent molten salts, neglecting the essential study of molten alkali chlorides, which are the solvent or main components in many applications. The alkali chlorides ternary system has a much lower melting point compared to the corresponding pure ones. There are few systematic reports on the study of ternary alkali metal chlorides systems in a temperature range of 900-1200 K and no comprehensive analysis on the correlation between the local structure and properties. In this context, our group determined to systematically investigate the ternary systems. This paper aimed to study the LiCl effect on eutectic NaCl-KCl systems (molar ration NaCl:KCl = 0.506:0.494). In this paper, molecular dynamics simulation was carried out to investigate the influence of LiCl concentration and temperature (900 K to 1200 K) on the local structure and properties of a molten LiCl-NaCl-KCl system. Correlations between the structure and properties were also analyzed.