Dinitrogen pentoxide (N2O5) is an important intermediate in the atmospheric chemistry of nitrogen oxides. Although there has been much research, the processes that govern the physical interactions between N2O5 and water are still not fully understood at a molecular level. Gaining quantitative insight from computer simulations requires going beyond the accuracy of classical force fields, while accessing length scales and time scales that are out of reach for high-level quantum chemical approaches. To this end we present the development of MB-nrg many-body potential energy functions for simulations of N2O5 in water. This MB-nrg model is based on electronic structure calculations at the coupled cluster level of theory and is compatible with the successful MB-pol model for water. It provides a physically correct description of long-range many-body interactions in combination with an explicit representation of up to three-body short-range interactions in terms of multidimensional permutationally invariant polynomials. In order to further investigate the importance of the underlying interactions in the model, a TTM-nrg model was also devised. TTM- nrg is a more simplistic representation that contains only two-body short-range interactions represented through Born-Mayer functions. In this work an active learning approach was employed to efficiently build representative training sets of monomer, dimer and trimer structures, and benchmarks are presented to determine the accuracy of our new models in comparison to a range of density functional theory methods. By assessing binding curves, distortion energies of N2O5, and interaction energies in clusters of N2O5 and water, we evaluate the importance of two-body and three-body short-range potentials. The results demonstrate that our MB-nrg model has high accuracy with respect to the coupled cluster reference, outperforms current density functional theory models, and thus enables highly accurate simulations of N2O5 in aqueous environments.

中文翻译：

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水中N2O5的高精度多体势模拟：基准，开发和验证

五氧化二氮（N2O5）​​是大气中氮氧化物的重要中间体。尽管已经进行了很多研究，但在分子水平上仍未完全理解控制N2O5与水之间的物理相互作用的过程。要从计算机仿真中获得定量见解，就需要超越经典力场的准确性，同时要获得高级量子化学方法无法达到的长度标度和时间标度。为此，我们提出了MB-nrg多体势能函数的开发，用于模拟水中的N2O5。此MB-nrg模型基于理论上耦合簇级别的电子结构计算，并且与成功的水MB-pol模型兼容。它结合多维置换不变多项式，提供了对长距离多体相互作用的物理正确描述，并结合了多达三体短程相互作用的显式表示。为了进一步研究模型中潜在相互作用的重要性，还设计了一个TTM-nrg模型。TTM-nrg是一种更简单的表示形式，仅包含通过Born-Mayer函数表示的两体短程相互作用。在这项工作中，采用了一种主动学习方法来有效地建立具有代表性的单体，二聚体和三聚体结构的训练集，并提出了一些基准来确定我们的新模型与一系列密度泛函理论方法相比的准确性。通过评估结合曲线，N2O5的变形能，以及N2O5和水簇中的相互作用能，我们评估了两体和三体短程电势的重要性。结果表明，我们的MB-nrg模型相对于耦合簇参考具有较高的精度，优于电流密度泛函理论模型，因此可以在水性环境中进行N2O5的高精度模拟。