We present in this contribution the first application of local correlation in the context of multicomponent methods. Multicomponent approaches allow for the targeted simulation of electrons together with other Fermions (most commonly protons) as quantum particles. These methods have become increasingly popular over the last years, particularly for the description of nuclear quantum effects (in strong hydrogen bonds, proton tunneling, and many more). However, most implementations are still based on canonical formulations of wave function theory, which we know for decades to be computationally inefficient for capturing dynamical correlation effects. Local correlation approaches, particularly with the use of pair natural orbitals (PNOs), enable asymptotically linear scaling of computational costs with very little impact on the overall accuracy. In this context, the efficient use of density fitting approximations in the integral calculation proves essential. We start by discussing our implementation of density-fitted NEO-MP2 and NEO-PNO-LMP2, upgrading the electronic correlation treatment up to PNO local coupled cluster level of theory. Several challenging examples are provided to benchmark the method in terms of accuracy as well as computational cost scaling. Following appropriate protocols, anharmonic corrections to localized X-H stretches can be applied routinely with little computational overhead.

中文翻译：

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多分量 Møller-Plesset 微扰理论中的局部电子相关


在这篇文章中，我们首次介绍了局部相关性在多分量方法背景下的应用。多组分方法允许将电子与其他费米子（最常见的质子）一起作为量子粒子进行有针对性模拟。这些方法在过去几年中变得越来越流行，特别是用于描述核量子效应（在强氢键、质子隧穿等中）。然而，大多数实现仍然基于波函数理论的规范公式，几十年来我们都知道，波函数理论在计算上对于捕获动态相关效应来说效率低下。局部相关方法，特别是使用成对自然轨道 （PNO） 的方法，可以实现计算成本的渐近线性缩放，而对整体精度的影响非常小。在这种情况下，在积分计算中有效使用密度拟合近似值被证明是必不可少的。我们首先讨论了密度拟合 NEO-MP2 和 NEO-PNO-LMP2 的实现，将电子相关处理升级到 PNO 局部耦合簇理论水平。提供了几个具有挑战性的示例，以在准确性和计算成本缩放方面对该方法进行基准测试。按照适当的协议，可以常规地对局部 X-H 拉伸进行非谐波校正，而计算开销很小。