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，以开发计算材料中跃迁速率的方法，并结合基于平面波的密度泛函理论（DFT）对能量学的描述。 寻找机制和传输速率的方法，如二聚体方法，攀登图像轻推弹性带方法，和最佳超平面过渡态理论，将被探索和实施。 方法学将应用于研究半导体中的扩散和生长，特别是可能在光电应用中有用的硅/锗表面土丘的生长。 模拟结合联合收割机DFT估计的传输率和动力学蒙特卡罗模拟的长时间动态将进行仔细比较，新的实验数据。 该项目还将开始开发计算凝聚态激发态的技术。 一个多体微扰展开，建立在修正的DFT平均场描述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致催化。 技术上重要的材料性质的第一性原理预测是一个长期的目标。 有效的理论化学技术与计算机集群或并行计算机上的实现相结合，最终可以实现这一难以捉摸的目标。 这项研究的结果预计将有助于量子点的新知识，量子点具有用作光开关的技术前景。 同时，二氧化钛的研究有望提高对这种材料重要应用的理解，包括有害微生物的破坏，癌细胞的灭活和溢油的清理。

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.