Decoding Van der Waals Impact on Chirality Transfer in Perovskite Structures: Density Functional Theory Insights

Chiral organic–inorganic perovskites exhibit unique
physicochemical
properties driven by the symmetry of monovalent organic cations. However,
an atomistic understanding of how chiral cations transfer their chirality
to the inorganic framework and the role played by van der Waals (vdW)
interactions in this process is still incomplete. In this work, we
report a theoretical investigation, based on density functional theory
calculations within the Perdew–Burke–Ernzerhof (PBE)
formulation for the exchange–correlation functional, into the
role of the vdW interactions in the chirality transfer process. For
that, we selected several vdW corrections, namely, Grimme (D2, D3,
D3­(BJ)), Tkatchenko–Scheffler (TS, TS+SCS, TS+HSI), density-dependent
energy correction (dDsC), and many-body scattering (MBD) energy method
correction. For the chiral perovskite systems, we selected a set of
chiral organic–inorganic perovskites with several dimensions,
namely, from zero-dimensional to three-dimensional, each having enantiomers
with R and S configurations. Based on a statistical treatment of the
relative errors of all lattice parameters with respect to experimental
data, we found that D3, D3­(BJ), TS, TS+SCS, TS+HSI, and MBD vdW are
the most accurate corrections to describe the equilibrium structural
properties of chiral perovskites using the PBE method. We identify
chirality-induced sequential asymmetries of distorted octahedrons
and propose angular descriptors to quantify them, where the orientations
of these distortions depend on the R or S nature of the chiral cations.
Furthermore, we demonstrate the importance of accurate vdW interactions
in precisely describing these asymmetric distortions. By means of
binding energies and charge-transfer analysis, we show that the impact
of vdW corrections on the charge distribution leads to a subtle strengthening
of hydrogen bonds between chiral cations and inorganic octahedra,
resulting in an increase in the binding energy. Finally, we identified
that the Rashba–Dresselhaus effect in two-dimensionality is
refined by vdW interactions.

手性有机-无机钙钛矿表现出由单价有机阳离子的对称性所驱动的独特的物理化学性质。然而，关于手性阳离子如何将手性传递给无机框架，以及范德华（vdW）相互作用在此过程中的作用，原子级别的理解仍然不完整。在本研究中，我们基于密度泛函理论计算，采用Perdew-Burke-Ernzerhof（PBE）公式中的交换-关联泛函，对vdW相互作用在手性传递过程中的作用进行了理论探讨。为此，我们选择了几种vdW校正方法，包括Grimme（D2、D3、D3-(BJ)）、Tkatchenko-Scheffler（TS、TS+SCS、TS+HSI）、密度依赖能量校正（dDsC）以及多体散射（MBD）能量方法校正。对于手性钙钛矿体系，我们选取了一系列具有不同维度（从零维到三维）的手性有机-无机钙钛矿，每个维度均包含具有R和S构型的对映异构体。通过对所有晶格参数相对于实验数据的相对误差的统计分析，我们发现D3、D3-(BJ)、TS、TS+SCS、TS+HSI和MBD vdW是使用PBE方法描述手性钙钛矿平衡结构性质的最精确校正。我们识别了扭曲八面体引起的序贯不对称性，并提出角度描述符来量化这些不对称性，其中这些扭曲的方向取决于手性阳离子的R或S性质。此外，我们证明了准确描述这些不对称扭曲的vdW相互作用的重要性。通过结合能和电荷转移分析，我们表明vdW校正对电荷分布的影响导致了手性阳离子与无机八面体之间氢键的微妙增强，从而增加了结合能。最后，我们确定了二维中的Rashba-Dresselhaus效应受到vdW相互作用的细化。