Ab Initio Calculation of Accurate Molecular Wave Functions

该项目旨在开发分子电子结构理论中的双基方法，由美国国家科学基金会理论和计算化学项目和高级科学计算部门共同支持。将开发使用压缩高斯基函数(明确相关的两粒子、高斯基函数的预定线性组合)来计算精确的从头算、小分子、电子波函数的方法。分子的基本参数将从优化的原子波函数中提取。将开发可扩展的算法，以便在并行计算机上实现。量子力学电子波函数是原子或分子中所有电子的空间和自旋坐标的数学函数。这些多体函数传统上用轨道来表示，即单电子坐标的函数。基于轨道的概念和计算方法在现代化学理论中发挥着核心作用，但使用现有超级计算机进行基于轨道的计算所能达到的精度实际上是有限的。该项目的目标是开发使用双星(一对电子坐标的显式函数)而不是轨道的改进计算方法。如果成功，这将显著提高气相反应速率理论预测的准确性，例如改进的地球大气计算机模型所需的预测。

This project to develop geminal-based methods in molecular electronic structure theory is supported jointly by the NSF Theoretical and Computational Chemistry Program and the the Advanced Scientific Computing Division. 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. The quantum mechanical electronic wavefunction is a mathematical function of the spatial and spin coordinates of all the electrons in the atom or molecule. These many-body functions are traditionally expressed in terms of orbitals, i.e. functions of the coordinates of a single electron. 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.