中文摘要：

传统单参考电子相关方法已经发展成熟，但很多时候无法正确描述共价键解离、双（多）自由基和激发态等电子之间相关性非常强的体系。近年来发展的多参考微扰理论和多参考耦合簇理论以多个行列式的线性组合为参考波函数，采用不同的方式有效考虑电子之间的动态相关，对强关联体系的描述取得了显著的改进。但根据理论出发点和精度求的不同发展出了许多多参考理论，仍无一个公认的、令人满意的方案。本文将结合与常见电子相关方法在理论框架和计算精度上的比较，详细阐述块相关理论的基本原理，并介绍基于块相关的“另类”多参考电子相关方法。最后本文还简单展望了多参考电子相关方法今后的发展趋势。

英文摘要：

Well-developed conventional single-reference electron-correlation methods usually fail to describe the dissociation of covalent bonds, di（or poly）radical systems or electronic structures of the excited states. Based on a multi-determinantal wave function, recently emerged multireference perturbation theories and coupled cluster theories can give drastically improved results; however, there is still no satisfactory scheme so far. In this monograph, alternative multireference perturbation theories and coupled cluster theories based on the ＂block-correlation＂ framework has been introduced and illustrated in detail, together with proper comparisons with other common electron-correlation methods. Future perspectives upon multireference theories have also been briefly discussed.