Early days of quantum crystallography: A personal account

Tsirelson, Vladimir G.

doi:10.1002/jcc.24893

Cited by 32 publications

(32 citation statements)

References 86 publications

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“…To our knowledge, QTAIM, which relies on the zero-flux boundary condition [35][36][37][38][39][40], is one of the current leading theoretical approaches used to study the nature and strength of hydrogen bonding and other non-covalent interactions. Two of its charge density-based topological descriptors, viz., the presence of a bond path (bp), and the presence of the (3,-1) bond critical point (bcp) between interacting atomic basins have proved very useful in inferring the presence of a chemical bonding in chemical systems [35][36][37][38][39][53][54][55][56][57][58][59][60]. Two of its other signatures, the sign of the Laplacian of the charge density ( 2  b ) and the sign of the total energy density (H b ) at a bcp, can be used (and have been recommended) to determine whether the interaction between two atomic basins in a given pair is ionic, covalent, or a mixture of the two [59][60][61][62][63][64][65].…”

Section: Methodsmentioning

confidence: 99%

Halogen in materials design: Revealing the nature of hydrogen bonding and other non-covalent interactions in the polymorphic transformations of methylammonium lead tribromide perovskite

Varadwaj

Marques

Yamashita

2018

Materials Today Chemistry

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Methylammonium lead tribromide (CH 3 NH 3 PbBr 3 ) perovskite as a photovoltaic material has attracted a great deal of recent interest. Factors that are important in their application in optoelectronic devices include their fractional contribution of the composition of the materials as well as their microscopic arrangement that is responsible for the formation of well-defined macroscopic structures. CH 3 NH 3 PbBr 3 assumes different polymorphs (orthorhombic, tetragonal and cubic) depending on the evolution temperature of the bulk material. An understanding of the structure of these compounds will assist in rationalizing how halogen-centered non-covalent interactions play an important role in the rational design of these materials. Density functional theory (DFT) calculations have been performed on polymorphs of CH 3 NH 3 PbBr 3 to demonstrate that the H atoms on C of the methyl group in CH 3 NH 3 + entrapped within a PbBr 6 4-perovskite cage are not electronically innocent, as is often contended. We show here that these H atoms are involved in attractive interactions with the surrounding bromides of corner-sharing PbBr 6 4-octahedra of the CH 3 NH 3 PbBr 3 cage to form Br•••H(-C) hydrogen bonding interactions. This is analogous to the way the H atoms on N of the -NH 3 + group in CH 3 NH 3 + form Br•••H(-N) hydrogen bonding interactions to stabilize the structure of CH 3 NH 3 PbBr 3 . Both these hydrogen bonding interactions are shown to persist regardless of the nature of the three polymorphic forms of CH 3 NH 3 PbBr 3 . These, together with the Br•••C(-N) carbon bonding, the Br•••N(-C) pnictogen bonding, and the Br•••Br lump-hole type intermolecular non-covalent interactions identified for the first time in this study, are shown to be collectively responsible for the eventual emergence of the orthorhombic geometry of the CH 3 NH 3 PbBr 3 system. These conclusions are arrived at from a systematic analysis of the results obtained from combined DFT, Quantum Theory of  Corresponding Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/xxxxxxx Atoms in Molecules (QTAIM), and Reduced Density Gradient Non-Covalent Interaction (RDG-NCI) calculations carried out on the three temperature-dependent polymorphic geometries of CH 3 NH 3 PbBr 3 .

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Section: Methodsmentioning

confidence: 99%

Halogen in materials design: Revealing the nature of hydrogen bonding and other non-covalent interactions in the polymorphic transformations of methylammonium lead tribromide perovskite

Varadwaj

Marques

Yamashita

2018

Materials Today Chemistry

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“…[19] The radial decay of the pseudo-atomsa nd the core and valence scattering factors in multipole modelsa re directly calculated from wavefunctions and hence the analytical shape of the refined electron density is significantly influenced by quantum chemistry.I ti si mportant to mention that, to ag ood approximation, the set of multipolar orbitals may be relatedt oa tomic hybridization states [20] and even to some individual orbital occupancies, for example that of d-orbitals in transition metals, [21] and more recently that of f-orbitals in lanthanides. [44] and Ref. [23] Cross-fertilized by charge-density research, ways of directly fitting the shapes of orbitals andw avefunctions to the mea-sured diffraction pattern were also devised.…”

Section: Introductionmentioning

confidence: 99%

Quantum Crystallography: Current Developments and Future Perspectives

Genoni

Bučinský

Claiser

et al. 2018

Chemistry A European J

123

114

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Crystallography and quantum mechanics have always been tightly connected because reliable quantum mechanical models are needed to determine crystal structures. Due to this natural synergy, nowadays accurate distributions of electrons in space can be obtained from diffraction and scattering experiments. In the original definition of quantum crystallography (QCr) given by Massa, Karle and Huang, direct extraction of wavefunctions or density matrices from measured intensities of reflections or, conversely, ad hoc quantum mechanical calculations to enhance the accuracy of the crystallographic refinement are implicated. Nevertheless, many other active and emerging research areas involving quantum mechanics and scattering experiments are not covered by the original definition although they enable to observe and explain quantum phenomena as accurately and successfully as the original strategies. Therefore, we give an overview over current research that is related to a broader notion of QCr, and discuss options how QCr can evolve to become a complete and independent domain of natural sciences. The goal of this paper is to initiate discussions around QCr, but not to find a final definition of the field.

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“…A disadvantage in this context is that BEDE and LONE do not reach the same sophistication in representing electron density as invarioms, transferable aspherical atom models (TAAMs) or Hirshfeld atom refinement; fine features of the EDD are not as well represented in the scattering factor model. 12 The goal of the new model is not to replace earlier charge-density or current quantum-crystallography (Massa et al, 1995;Grabowsky et al, 2017;Tsirelson, 2018) Concept and the different options m for the LONE instruction. The H-atom treatment corresponding to the same m is also shown, including angle expectations according to the VSEPR model.…”

Section: Lone Pair Electron Density: Lonementioning

confidence: 99%