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Large-scale ab initio simulations of MAS DNP enhancements using a Monte Carlo optimization strategy
The Journal of Chemical Physics ( IF 4.4 ) Pub Date : 2018-10-19 , DOI: 10.1063/1.5042651
Frédéric A. Perras 1 , Marek Pruski 1, 2
Affiliation  

Magic-angle-spinning (MAS) dynamic nuclear polarization (DNP) has recently emerged as a powerful technology enabling otherwise unrealistic solid-state NMR experiments. The simulation of DNP processes which might, for example, aid in refining the experimental conditions or the design of better performing polarizing agents, is, however, plagued with significant challenges, often limiting the system size to only 3 spins. Here, we present the first approach to fully ab initio large-scale simulations of MAS DNP enhancements. The Landau-Zener equation is used to treat all interactions concerning electron spins, and the low-order correlations in the Liouville space method is used to accurately treat the spin diffusion, as well as its MAS speed dependence. As the propagator cannot be stored, a Monte Carlo optimization method is used to determine the steady-state enhancement factors. This new software is employed to investigate the MAS speed dependence of the enhancement factors in large spin systems where spin diffusion is of importance, as well as to investigate the impacts of solvent and polarizing agent deuteration on the performance of MAS DNP.

中文翻译:

使用蒙特卡洛优化策略的MAS DNP增强的大规模从头算模拟

魔角旋转(MAS)动态核极化(DNP)最近作为一种强大的技术而出现,可以实现不现实的固态NMR实验。然而,DNP工艺的模拟可能例如有助于改善实验条件或设计性能更好的偏振剂,但面临着巨大挑战,通常将系统尺寸限制为仅3次旋转。在这里,我们介绍了完全从头开始的第一种方法MAS DNP增强的大规模模拟。Landau-Zener方程用于处理与电子自旋有关的所有相互作用,而Liouville空间方法中的低阶相关性用于精确处理自旋扩散及其与MAS速度的关系。由于无法存储传播子,因此使用蒙特卡洛优化方法确定稳态增强因子。此新软件用于研究自旋扩散很重要的大型自旋系统中增强因子的MAS速度依赖性,以及研究溶剂和偏振剂氘化对MAS DNP性能的影响。
更新日期:2018-10-19
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