Development of Algorithms for DFT Calculations of the Rate of Transitions In Ground and Excited States

华盛顿大学的Hannes Jonsson得到了理论和计算化学计划的支持，该计划开发了结合基于平面波的密度泛函理论(DFT)的能量学描述来计算材料中的跃迁速率的方法。将探索和实施寻找机制和传输率的方法，如二聚体法、爬坡像推弹性带法和最佳超平面过渡态理论。将采用方法学研究半导体中的扩散和生长，特别是在光电应用中可能有用的硅/锗表面丘的生长。将进行结合传输速率的DFT估计和长时间动力学的动力学蒙特卡罗模拟的模拟，以便能够与新的实验数据进行仔细的比较。该项目还将开始开发计算凝聚态中激发态的技术。对DFT平均场描述进行修正的多体微扰展开将在小分子上进行测试，然后应用于研究二氧化钛表面的光学性质和光诱导催化作用。对具有重要技术意义的材料性能进行第一性原理预测是一个长期目标。将有效的理论化学技术与在计算机集群或并行计算机上的实施相结合，最终可以实现这一难以实现的目标。这项研究的结果预计将有助于对量子点的新认识，量子点在技术上有望用作光开关。此外，二氧化钛光催化的研究有望提高人们对这种材料的重要应用的理解，这些应用包括有害微生物的破坏、癌细胞的灭活和漏油的清理。

Hannes Jonsson of the University of Washington is supported by the Theoretical and Computational Chemistry Program to develop methods for calculating transition rates in materials in combination with a plane-wave-based density functional theory (DFT) description of the energetics. Methods for finding mechanisms and transmission rates, such as the dimer method, climbing image-nudged elastic band method, and optimal hyperplanar transition state theory, will be explored and implemented. Methodologies will be applied to study diffusion and growth in semiconductors, in particular the growth of silicon/germanium surface mounds that may be useful in opto-electronic applications. Simulations that combine DFT estimates of transmission rates and kinetic Monte Carlo simulations of long time dynamics will be carried out to enable careful comparisons to new experimental data. This project will also begin developing techniques to calculate excited states in condensed matter. A many-body perturbation expansion that builds in corrections to the DFT mean field description will be tested on small molecules, and then applied to study optical properties and photoinduced catalysis on titanium dioxide surfaces. The first principles prediction of technologically important material properties is a longstanding goal. The combination of efficient theoretical chemistry techniques and implementation on computer clusters or parallel computers finally can bring this elusive goal within reach. The outcomes of this research are anticipated to contribute to new knowledge of quantum dots, which have technological promise for use as optical switches. As well, studies of titanium dioxide photocatalysis are expected to improve understanding of important applications for this material that include harmful microorganism destruction, cancer cell inactivation, and oil spill cleanup.