Development and Application of Methods for the Calculation of Accurate Structures, Energetics and Properties of Molecules

彼得·泰勒是由理论和计算 化学系化学专业与新技术 高级科学计算部门的计划，继续他的 研究发展和应用方法， 精确的结构、能量学和性质的计算 分子。 将制定方法， 从头算，小分子，电子波函数 高斯孪生（Gaussian geminals） 显式相关、两粒子、高斯基函数）。 偕 分子参数将从优化的原子中提取 波函数 将开发可扩展的算法以供实施 在并行计算机上。 泰勒断言双电子基组 提供更快的收敛，从而提供一条更高的 小型系统的准确性，以及扩展现有水平的方法， 精确到更大的分子。 应用程序包括确定 的非谐频率和振动强度， 分子，以及涉及有机物电子光谱学的研究 过渡金属系统和小元素簇。 基于轨道的概念和计算方法在 现代化学理论，但有一个实际的限制，以准确性 这在使用现有超级计算机的轨道计算中是可以实现的。 这个项目的目标是开发改进的计算方法 使用双（一对的坐标的显式函数， 而不是轨道。 如果成功，这将大大 提高气相反应理论预测的准确性 例如，改进地球的计算机模型所需的利率 气氛

Peter Taylor is jointly funded by the Theoretical and Computational Chemistry Program in the Chemistry Division and the the New Technologies Program in the Advanced Scientific Computing Division to continue his research in the development and application of methods for the calculation of accurate structures, energetics, and properties of molecules. Methods will be developed for the computation of accurate, ab initio, small molecule, electronic wavefunctions using contracted Gaussian geminals (predetermined linear combinations of explicitly-correlated, two-particle, Gaussian basis functions). Geminal parameters for molecules will be extracted from optimized atomic wavefunctions. Scalable algorithms will be developed for implementation on parallel computers. Taylor asserts that two-electron basis sets offer much more rapid convergence and thus provide a route to higher accuracy for small systems, and a way to extend existing levels of accuracy to larger molecules. Applications include the determination of anharmonic frequencies and vibrational intensities for small molecules, and studies involving the electronic spectroscopy of organic and transition-metal systems and small elemental clusters. Orbital-based concepts and computational methods play a central role in modern chemical theory, but there is a practical limit to the accuracy attainable in orbital-based computations using existing supercomputers. The goal of this project is to develop improved computational methods using geminals (explicit functions of the coordinates of a pair of electrons) rather than orbitals. If successful, this will significantly increase the accuracy of theoretical predictions of gas phase reaction rates such as those required for improved computer models of the earth's atmosphere.