Peng: A program for transport properties of low-density binary gas mixtures

The fundamental properties of molecules bridge experiment and theory. Transport properties (diffusion, thermal diffusion, thermal conductivity and viscosity) of binary mixtures are measurable in experiments, and well-defined in theory, but difficult to compute with high accuracy. In addition to high-accuracy inter-molecular potential energy curves (PECs), a reliable and high-order solution program that compute the properties based on the PECs is required. In this work, we present a computer program called Peng that performs the collision integration numerically, and solves the Boltzmann equation in Chapman–Enskog fashion. The program has been devised to perform both parts of the solution procedure to arbitrary order, so that no hard-coded limitation will prevent a user from computing at higher precision, except the amount of RAM and the required computational time. Peng is well-designed in an Object-Oriented Programming (OOP) fashion, which make the program clear and easy to modify. In addition to the end-user oriented program, Peng is also compiled as a dynamic shared library that may readily be extended and embedded in users' programs.

分子的基本性质构筑了实验与理论的桥梁。二组分混合物的传输性质（扩散、热扩散、热导率和粘度）在实验中可测，在理论上定义明确，但难以精确计算。除了高精度的分子间势能曲线（PECs）外，还需一个可靠且高阶的解决方案程序，以基于PECs计算相关性质。在本研究中，我们提出了一款名为Peng的计算机程序，该程序通过数值积分实现碰撞积分，并以Chapman-Enskog方式求解玻尔兹曼方程。Peng程序被设计成能执行求解过程的任意阶部分，以确保用户在计算时不受硬编码限制，除非受限于内存容量和计算时间。Peng程序以面向对象编程（OOP）的方式进行精心设计，使得程序结构清晰且易于修改。除了面向最终用户的程序外，Peng还编译为动态共享库，便于用户程序对其进行扩展和嵌入。