Developing the MCTDH Quantum Dynamics Code: Accurate Direct Dynamics of Non-Adiabatic Phenomena

理解吸收光子后分子中的能量流对于理解它们的光激活特性是很重要的。这些在一系列技术中都很重要，比如收集太阳能和数据存储，以及理解光稳定性和通过光化学途径获得新分子。这种能量流是复杂的，因为有许多不同的途径（通道）可用。特别重要的是所谓的非绝热途径，它允许分子进行化学性质（电子状态）的变化，从而有效地在瞬间控制分子的进化。不幸的是，不可能先验地说哪些途径对特定分子最重要，计算机模拟通过模拟激发后的势能面和分子动力学，在回答这个问题方面发挥了重要作用。用于模拟激发态动力学的计算机代码正变得越来越强大和有用。然而，仍然没有可用的代码可以捕获所有的量子力学效应，这些效应通常是我们感兴趣的大分子。MCTDH包是少数几个能够以一种通用的、用户友好的方式准确处理这些问题的代码之一。代码的开发部分实现了一种新颖的方法，DD-vMCG算法。这有望使用所谓的直接动力学来准确地处理感兴趣的分子，它将分子结构变化的动态模拟与一个单独的程序相结合，该程序只在需要时计算势能面，从而节省了大量的工作。初步研究支持这一观点。这个DD-vMCG代码在许多研究中显示了它的潜力。现在需要对其进行开发，使其高效、易于使用，并能以可持续的方式进行开发。科学软件的可持续发展对其生存和适应科学进步至关重要。计划中的工作将确保这种方法在经过多年的发展后能够发挥其潜力，并被科学界用来帮助理解和设计分子的行为，并最终在光的存在下进行控制。

Understanding the energy flow in molecules after absorbing a photon of light is important to understand their light-activated properties. These are important in a range of technologies, such as harvesting solar energy and data storage, as well as understanding photo-stability and deriving new molecules via photochemical pathways. This energy flow is complex, as a number of different pathways (channels) are available. Of particular importance are what are termed non-adiabatic pathways that allow a molecule to undergo a change of chemical character (electronic state) effectively instantaneously and so dominate the molecular evolution. Unfortunately it is impossible to say a priori which pathways are most important for a particular molecular, and computer simulations have a large role to play in answering this question by modelling the potential energy surfaces and molecular dynamics after excitation.Computer codes for simulating excited-state dynamics are becoming more powerful and useful. However, there is still no code available that can capture all of the quantum mechanical effects required for the often large molecules of interest. The MCTDH package is one of the few codes that is able to treat these problems accurately in a general, user-friendly way. A development part of the code implements a novel method, the DD-vMCG algorithm. This promises to be able to accurately treat the molecules of interest using what is termed direct dynamics, which couples the dynamical simulation of the changes in molecular structure to a separate program that calculates the potential energy surfaces only when required, thus saving much of the work. Initial studies support this.This DD-vMCG code has shown its potential in a number of studies. It now needs to be developed so that it is efficient, easy to use, and can be developed in a sustainable manner. The sustainable development of scientific software is crucial for it to survive and adapt as science progresses. The planned work will ensure that this method will be able to fulfill its potential after many years of development and be used by the scientific community to help understand and engineer how molecules behave and can ultimately be controlled in the presence of light.