Tawfik Sherif Abdulkader, Walsh Tiffany R
Applied Artificial Intelligence Institute, Deakin University Geelong Victoria 3216 Australia
Institute for Frontier Materials, Deakin University Geelong Victoria 3216 Australia.
Chem Sci. 2025 May 1. doi: 10.1039/d5sc00175g.
In the Car-Parrinello molecular dynamics (CPMD) formalism, orbitals can be assigned different effective masses according to whether the orbital is occupied by a hole or an electron, and such masses affect the response of the orbitals to their environment. Inspired by this, we introduce and implement a novel modification of CPMD, HoleMass CPMD, in which a hole, which is a partially empty orbital, is assigned a fictitious mass that is different from fully occupied orbitals. Despite the simplicity of the approach, we find that it solves a key problem in first principles molecule dynamics simulation: for a set of carefully assigned mass values, the method is able to successfully simulate photoinduced chemical reactions, exemplified here by the ring-opening reaction in oxirane within a few femtoseconds, and cyclobutene, within a few picoseconds. Our method can reproduce the CO ring-opening of oxirane, and the correct isomerization sequence for cyclobutene: when the ring opens, the first isomer that forms is the isomer, followed by the isomer. Our method has been implemented in the Car-Parrinello package of QuantumEspresso and is available as an open-source contribution. The HoleMass CPMD method provides a new quantum chemistry tool for the simulation of excitation dynamics in molecules, and can also be applied for modelling charge localization effects in materials systems.
在Car-Parrinello分子动力学（CPMD）形式体系中，根据轨道是被空穴还是电子占据，可给轨道赋予不同的有效质量，且这些质量会影响轨道对其环境的响应。受此启发，我们引入并实现了一种对CPMD的新颖改进——空穴质量CPMD，其中，空穴（即部分空的轨道）被赋予与完全占据轨道不同的虚拟质量。尽管该方法很简单，但我们发现它解决了第一性原理分子动力学模拟中的一个关键问题：对于一组精心设定的质量值，该方法能够成功模拟光致化学反应，本文以环氧乙烷在几飞秒内的开环反应以及环丁烯在几皮秒内的反应为例。我们的方法能够重现环氧乙烷的CO开环反应以及环丁烯正确的异构化顺序：当环打开时，首先形成的异构体是 异构体，随后是 异构体。我们的方法已在QuantumEspresso的Car-Parrinello软件包中实现，并作为开源贡献可供使用。空穴质量CPMD方法为模拟分子中的激发动力学提供了一种新的量子化学工具，也可用于模拟材料系统中的电荷局域化效应。
