Molecules in Non-Perturbative Fields: Improving Time-Dependent Density Functional Approximations and Electron-Ion Correlation Methods

CUNY Hunter College的Neepa Maitra获得了化学系化学理论，模型和计算方法项目的奖项，以开发用于模拟电子和离子相关动力学的理论和计算方法。 材料研究部的凝聚态物质和材料计划也有助于获得该奖项。理解电子和离子的运动对于理解和预测许多涉及物质与光相互作用的现象非常重要。 这些现象具有基础性和技术性的重要性，例如，将光转换为电的光伏器件，激光器和使用激光控制化学过程。 控制这种运动的方程已经知道了90年。 然而，对于除最简单的系统之外的所有系统，精确求解这个方程太困难了。 这个困难是由于相关运动而产生的。每个电子的运动会影响其他电子的运动以及每个离子的运动，反之亦然。 含时密度泛函理论（TDDFT）是求解该方程的一种有效、近似和流行的方法。 在许多情况下，今天使用的特定近似是不够的，导致电子动力学中不可预测的错误。 Maitra和她的同事基于严格的理论考虑开发了改进的近似。 本科生和研究生都参加了这项前沿研究。Maitra在纽约市立大学组织小型研讨会，向更广泛的纽约地区的科学家开放。 她与现有的 在亨特学院的计划，以促进发展的代表性不足的少数民族科学家Maitra和她的同事开发改进，强大的近似电子动力学通过施加精确的条件，使理论可以用于实时动力学与尽可能多的信心和可预测性密度泛函理论用于基态能量和结构。 我们的目标是克服TDDFT的几个限制，目前防止它被可靠地用于实时电子动力学的非微扰制度，以及激发光谱。 电子和离子的动力学耦合使用的方法的基础上最近推出的第一性原理精确因式分解方法。 这包括开发实用的混合量子（半）相关的电子离子动力学，包括电子退相干和波包分支的第一原理的经典计划。

Neepa Maitra of CUNY Hunter College is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop theoretical and computational approaches for simulating the correlated dynamics of electrons and ions. The Condensed Matter and Materials program in the Division of Materials Research also contributes to this award. Understanding the motion of electrons and ions is important for understanding and predicting many phenomena that involve the interaction of matter with light. These phenomena have both fundamental and technical importance, for example, photovoltaic devices which convert light into electricity, photocatalysis, and control of chemical processes using lasers. The equation that governs this motion has been known for 90 years. For all but the simplest systems, however, it is too difficult to solve this equation exactly. This difficulty arises because of correlated motion. Each electron's motion affects every other electron's motion as well as each ion's, and vice-versa. Time-dependent density functional theory (TDDFT) is an efficient, approximate and popular approach to solving this equation. In many cases, the particular approximations used today are not adequate, causing unpredictable errors in the electron dynamics. Maitra and her coworkers develop improved approximations based on rigorous theoretical considerations. Both undergraduate and graduate students participate in this cutting-edge research. Maitra organizes mini-workshops at CUNY open to scientists in the wider New York area. She works with existing programs at Hunter College to promote the development of underrepresented minority scientists Maitra and her coworkers develop improved, robust approximations for electron dynamics by imposing exact conditions, so that the theory can be used for real-time dynamics with as much confidence and predictability as density functional theory is used for ground-state energies and structures. The goals is to overcome several limitations of TDDFT that currently prevent it from being used reliably for real-time electron dynamics in the non-perturbative regime, as well as for excitation spectra. The dynamics of the electrons and ions are coupled by using a method based on the recently-introduced first-principles exact factorization approach. This includes developing practical mixed quantum-(semi)classical schemes for correlated electron-ion dynamics that include electronic decoherence and wave packet-branching from first-principles.