New Developments and Applications in Coupled Clusters and Density Dependent Electronic Structure Methods

这项研究得到了NSF理论和计算的支持。 化学计划 耦合团簇和密度泛函方法 分子电子结构理论将被研究和比较， 寻找密度泛函理论的从头算衍生泛函。 一个改进的计划将探讨计算的三元组 Brueckner双曲理论中的微扰修正。 这些 计算方法将应用于过渡金属的研究 系统和燃烧过程。 原则上，分子系统的物理和化学性质 可以从多体波函数（传统的AB 从头算理论）或从电子电荷密度（密度泛函 理论）。 目前存在高度发达的计算机程序， 将这两个理论中的任何一个应用于各种各样的 化学问题。 从头算方程，特别是那些耦合 集群理论，可能需要使用超级计算机进行非常繁重的计算， 但这些方程都是建立在成熟的数学基础上， 物理原则。 密度泛函理论的方程提供了 显著的计算优势，但仍然存在严重的问题 关于这些方程的精确形式。 本比较 从头算和密度泛函方法的研究试图发展 改进的分子电子结构计算方法 联合收割机结合这两种不同的强度的计算 形式主义 这种改进的密度泛函的发展， 理论是现代理论化学的一个热点。 一 这一领域的突破将大大扩展分子的尺寸， 可以使用以下方法进行可靠理论预测的系统 现代计算机，而且几乎肯定会发现广泛和直接 应用程序. 过渡金属的实验计算 化合物构成了新的合理设计的最初步骤 工业催化剂

This research is supported by the NSF theoretical and computational chemistry program. Coupled-cluster and density functional methods in molecular electronic structure theory will be studied and compared to search for an ab-initio-derived-functional for density functional theory. An improved scheme will be explored for computing the triples perturbative correction in Brueckner doubles theory. These computational methods will be applied to the study of transition metal systems and combustion processes. In principle, the physical and chemical properties of molecular systems can be obtained from either the many-body wavefunction (traditional ab initio theory) or from the electronic charge density (density functional theory). There presently exist highly developed computer programs for applying either of these two theories to any of a wide variety of chemical problems. Ab initio equations, particularly those of coupled cluster theory, may require very heavy computations using supercomputers, but these equations are firmly based on well established mathematical and physical principles. The equations of density functional theory offer significant computational advantages, but serious questions remain concerning the precise form of these equations. The present comparative study of ab initio and density functional methods attempts to develop improved computational methods for molecular electronic structure computations which combine the strengths of these two different formalisms. The development of such an improved density functional theory is currently a hot topic in modern theoretical chemistry. A breakthrough in this area will greatly extend the size of molecular systems for which reliable theoretical predictions can be made using modern computers, and will almost certainly find wide and immediate application. The proposed test calculations on transition metal compounds constitute the initial steps toward the rational design of new industrial catalysts.