Abstract:
Warm dense plasma is subject to extreme physical conditions of high temperature and high density, where atoms tend to be partially ionized, forming a complex system with multiple ionic charge states coexisting. Investigating the regulatory mechanism of different ionic charge states on the microscopic structure and macroscopic transport properties of the system is a key scientific issue in inertial confinement fusion and astrophysical research. In this work, a multi-ion molecular dynamics (MIMD) simulation method based on the Yukawa potential is adopted, combined with the Saha equation to calculate the abundance of ions in different charge states. The structure and transport properties of warm dense plasma under a multi-charge-state environment are systematically investigated. Simulation results show that the local order of the system is mainly regulated by both temperature and density, while the ionic charge state determines the specific characteristics of the local atomic arrangement. Due to the stronger Coulomb repulsion between high-charge-state ions, their radial distribution functions are significantly reduced. Correspondingly, the ionic self-diffusion coefficient decreases monotonically with increasing charge state, increases with rising temperature, and decreases with increasing system density, exhibiting clear regularity. In addition, a dynamically screened Yukawa potential considering ion velocity is introduced for comparative simulations. The results reveal that the dynamic screening effect increases the effective screening length of the system and enhances the interionic Coulomb interaction, accelerating the decay rate of the velocity correlation function and ultimately leading to a reduction in the self-diffusion coefficient. This effect is more pronounced under high-temperature and low-density conditions. In single-element systems, low-charge-state ions are more strongly modulated by dynamic screening.