Thermodynamic properties of diatomic CO, CN, C₂ and CO⁺ in CO₂-N₂ plasmas

The reliable data of plasma thermodynamic properties are of vital significance for aerodynamic modelling and plasma dynamics simulation. In this work, we have thoroughly evaluated the thermodynamic properties of diatomic CO, CN, C₂ and CO⁺ by making use of a more rigorous approach. The internal energy levels were precisely determined by solving rotational dependence of the radial Schrödinger equation over a set of potential curves. The RKR method was used to generate the low-lying potential curves, while the ab initio results reported by the recent publications were selected for the potential curves of high-lying states. More electronic states were considered in this work than in previous publications, which helps to make the calculated results more accurate at high temperatures. The predicted results were verified by the available values in the recent studies and the relative deviations were systematically evaluated. The maximum relative difference of the equilibrium partition function is less than 7.7% for all species and not larger than 15.3% for equilibrium dimensionless specific heat.等离子体热力学性质的可靠数据，对于气动建模与等离子体动力学模拟均具有至关重要的意义。本研究采用更为严谨的方法，对双原子一氧化碳（CO）、氰基（CN）、二碳分子（C₂）及一氧化碳阳离子（CO⁺）的热力学性质开展了全面评估。通过针对一组势能曲线求解径向薛定谔方程的转动依赖性，精准确定了体系的内能级结构：采用里德堡-克莱因-里斯（Rydberg-Klein-Rees, RKR）方法生成低激发态势能曲线，高激发态的势能曲线则选取自近期文献报道的从头算（ab initio）结果。相较于以往研究，本工作考虑了更多的电子态，这使得高温下的计算结果更为准确。研究通过近期文献中的可用数据对预测结果进行了验证，并对相对偏差开展了系统评估。结果显示，所有研究物种的平衡配分函数最大相对偏差均小于7.7%，平衡无量纲比热容的最大相对偏差不超过15.3%。