Many-Electron Densities and Reduced Density Matrices
Many-Electron Densities and Reduced Density Matrices
复制标题
DOI：
10.1007/978-1-4615-4211-7
复制
发表时间：
2012-11
期刊：
影响因子：
--
通讯作者：
J. Cioslowski
中科院分区：
文献类型：
--
作者：
J. Cioslowski
科学的进步是突飞猛进的，而不是随时间线性发展的。一个新的概念或方法最初引起很大兴趣，但进入数年或数十年的安静期，然后突然重新成为新的令人兴奋的研究的焦点，这种情况并不罕见。降密度矩阵（又名 N 矩阵或 RDM）当然就是这种情况，当制定辅助但重要的 N 表示条件的前景变得相当黯淡时，其对量子化学方法的极大简化的承诺就消失了。然而，即使在最初的失望之后的时期，2-矩阵及其单粒子对应物在现代电子结构理论的形式体系中已经无处不在，进入一阶响应性质的相关级表达式，产生了在构型相互作用方法和电子波函数的严格分析中使用的自然自旋轨道，并允许通过扩展的库普曼斯定理直接计算电离势。 Nakatsuji、Valdemoro 和 Mazziotti 最近的研究使 RDlvls 概念得到复兴，将其从解释工具和辅助量的角色提升为新电子相关形式主义的中心变量。由于 RDM 提供的信息经济性，这些形式主义在表述的简洁性和优雅性方面超越了传统方法。因此，他们有望开启量子化学的全新篇章。
Science advances by leaps and bounds rather than linearly in time. I t is not uncommon for a new concept or approach to generate a lot of initial interest, only to enter a quiet period of years or decades and then suddenly reemerge as the focus of new exciting investigations. This is certainly the case of the reduced density matrices (aka N-matrices or RDMs), whose promise of a great simplification of quantum-chemical approaches faded away when the prospects of formulating the auxil iary yet essential N-representability conditions turned quite bleak. How ever, even during the period that followed this initial disappointment, the 2-matrices and their one-particle counterparts have been ubiquitous in the formalisms of modern electronic structure theory, entering the correlated-level expressions for the first-order response properties, giv ing rise to natural spinorbitals employed in the configuration interaction method and in rigorous analysis of electronic wavefunctions, and al lowing direct calculations of ionization potentials through the extended Koopmans' theorem. The recent research of Nakatsuji, Valdemoro, and Mazziotti her alds a renaissance of the concept of RDlvls that promotes them from the role of interpretive tools and auxiliary quantities to that of central variables of new electron correlation formalisms. Thanks to the economy of information offered by RDMs, these formalisms surpass the conven tional approaches in conciseness and elegance of formulation. As such, they hold the promise of opening an entirely new chapter of quantum chemistry.