提出了一个改进的密度泛函理论模型.该模型同时考虑了流体中两分子和三分子相互作用对体系Helm hlotz自由能的贡献,对Ar,N2,CH4,CO2等四种流体的气液界面张力进行了预测,结果与实验值均吻合良好.通过与仅考虑两分子作用的理论计算值和分子模拟值进行比较,表明流体中的三分子相互作用对描述非均相流体的结构与性质有重要影响. An improved density functional theory model is proposed. The model also considers the contribution of the interaction between two molecules and three molecules in the system to the Helm hlotz free energy of the system. For the gas-liquid interface of four fluids such as Ar, N2, CH4 and CO2 The results are in good agreement with the experimental data.Comparing with the theoretical calculation and the molecular simulation only considering the interaction of two molecules, it is shown that the three-molecule interaction in the fluid is of great importance for describing the structure and properties of the heterogeneous fluid Significant influence.