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本文提出一个新的扩大模型空间的方案用于改进多参考态二级微扰理论(MRPT2)计算.新方案保持了原方案中扩大模型空间之前的简单程序结构,理论上完全可以避免势能面计算中入侵态的出现,并在一系列比较计算中得到证实.新MRPT2程序是研究分子激发态和电子光谱的有用工具.
In this paper, a new scheme to expand the model space is proposed to improve the MRPT2 calculation. The new scheme preserves the simple program structure before expanding the model space in the original scheme and theoretically can completely avoid the potential energy surface calculation The appearance of invasiveness was confirmed in a series of comparative calculations.The new MRPT2 program is a useful tool to study molecular excited states and electron spectra.