作者以化学元素的稳定单质为基准,推演出了任意物质M_i(相态Ω)的热力学生成活度{相态Ω)的函数形式:?D_Ω数值的大小体现着相态Ω的热力学相对稳定性.根据集合论原理沿D(稳定性)座标取极大值的方法把物理性质互不连续的各个异相态连结在一起,建立了单元系在T-p面上的优势分布方程(PSDE):■作者以H_2O为实例,计算了T-p相图,与实验相图基本一致. Based on the stable elements of chemical elements, the authors derive the function form of thermodynamic activity {phase Ω) of any material M_i (phase Ω): The magnitude of D_Ω reflects the thermodynamic relative stability of phase Ω According to the theory of set theory, taking the D (stability) coordinates as the maximum value, the disparate physical states are connected together to form the dominant distribution equation (PSDE) of the unit system on the Tp plane: ■ By taking H_2O as an example, the author calculates the Tp phase diagram which is basically the same as the experimental phase diagram.