X-ray diffraction (XRD) has evolved significantly since its inception, becoming a crucial tool for material structure characterization. Advancements in theory, experimental techniques, diffractometers and detection technology have led to the acquisition of highly accurate patterns, surpassing previous expectations. Extracting comprehensive information from these patterns necessitates different models due influence both electron density thermal motion on diffracted beam intensity. While...

A revolution in resolution is occurring now electron microscopy arising from the development of methods for imaging single particles at cryogenic temperatures and obtaining diffraction data nanocrystals small organic molecules or macromolecules. Near-atomic even atomic molecular structures can be achieved. The basis these scattering an beam due to electrostatic potential sample. To analyse high-quality experimental data, it necessary use appropriate factors. independent atom model (IAM)...

Hydrogen is present in almost all of the molecules living things. It very reactive and forms bonds with most elements, terminating their valences enhancing chemistry. X-ray diffraction common method for structure determination. depends on scattering X-rays from electron density, which means single hydrogen difficult to detect. Generally, neutron data are used determine accurate position atoms. However, requirement good quality crystals, costly maintenance limited number facilities that these...

A fast and accurate operational model of electron density is crucial in many scientific disciplines including crystallography, molecular biology, pharmaceutical, structural chemistry. In quantum the aspherical refinement crystal structures becoming increasingly popular because its description terms physically meaningful properties. The transferable atom (TAAM) quick precise, though it requires a robust algorithm for typing coverage most types present small organic molecules. Thus, University...

Hydrogen positions in hydrides play a key role hydrogen storage materials and high-temperature superconductors. Our recently published study of five crystal structures transition-metal-bound hydride complexes showed that using aspherical atomic scattering factors for Hirshfeld atom refinement (HAR) resulted systematic elongation metal–hydrogen bonds compared to spherical with the Independent Atom Model (IAM). Even though only standard-resolution X-ray data was used, highest-quality data, we...

Form factors based on aspherical models of atomic electron density have brought great improvement in the accuracies hydrogen atom parameters derived from X-ray crystal structure refinement. Today, two main groups such are available, banks transferable densities parametrized using Hansen-Coppens multipole model which allows for rapid evaluation form and Hirshfeld refinement (HAR)-related methods usually more accurate but also slower. In this work, a that combines ideas utilized approaches is...

A new computer program for post-processing analysis of quantum-chemical electron densities is described. The code can work with Slater- and Gaussian-type basis functions arbitrary angular momentum. It has been applied to explore the basis-set dependence density its Laplacian in terms local integrated topological properties. Our analysis, including Gaussian/Slater sets up sextuple/quadruple-zeta order, shows that these properties considerably depend on choice type number primitives utilized...

It has been recently established that the accuracy of structural parameters from X-ray refinement crystal structures can be improved by using a bank aspherical pseudoatoms instead classical spherical model atomic form factors. This comes, however, at cost increased complexity underlying calculations. In order to facilitate adoption this more advanced electron density broader community crystallographers, new software implementation called DiSCaMB , `densities in chemistry and molecular...

Hirshfeld atom refinement is one of the most successful methods for accurate determination structural parameters hydrogen atoms from X-ray diffraction data. This work introduces a generalization method [generalized (GAR)], consisting application various partitioning electron density into atomic contributions. These were tested on three organic structures using following partitions: Hirshfeld, iterative stockholder, minimal basis stockholder and Becke. The effects partition choice also...

Positions and anisotropic thermal motion of H-Atoms bound to heavy atoms in transition-metal hydride complexes were successfully refined using Hirshfeld Atom Refinement (HAR) against low resolution X-ray diffraction data.

Aspherical atom refinement is the key to achieving accurate structure models, displacement parameters, hydrogen-bond lengths and analysis of weak interactions, amongst other examples. There are various quantum crystallographic methods perform aspherical refinement, including Hirshfeld (HAR) transferable model (TAAM) refinement. Both HAR TAAM have their limitations advantages, former being more latter faster. With advent non-spherical atoms in Olex2 ( NoSpherA2 ), it now possible overcome...

Hirshfeld atom refinement (HAR) is one of the most effective methods for obtaining accurate structural parameters hydrogen atoms from X-ray diffraction data. Unfortunately, it also relatively computationally expensive, especially larger molecules due to wavefunction calculations. Here, a fragmentation approach has been tested as remedy this problem. It gives an order magnitude improvement in computation time organic systems and few times faster metal–organic at cost only minor differences...

Water is an essential chemical compound for living organisms, and twenty of its different crystal solid forms (ices) are known. Still, there many fundamental problems with these structures such as establishing the correct positions thermal motions hydrogen atoms. The list ice not yet complete DFT calculations have suggested existence additional - to date unknown phases. In structures, neither neutron diffraction nor X-ray methods can easily solve problem atom disorder or accurately determine...

Various models applied to DFT structures and energies of 2-D 3-D aromatic molecules shed new light on the effects strain aromaticity in these systems. The cyclic π electron delocalisation does not stabilize fullerene C60 formation; 5–6 6–6 CC bonds have near-identical bond stretch potentials.

The availability of atomic resolution experimental maps electrostatic potential from 3D electron diffraction (3D ED) extends the possibility investigating beyond determination non-H-atom positions. However, accurate tools to calculate this for macromolecules, without use expensive quantum calculations, are lacking. University at Buffalo Data Bank (UBDB) gathers atom types that can be used via structure-factor calculations. Here, transferable aspherical model (TAAM) is applied with UBDB...

The advancement in 3D electron diffraction (3D ED) techniques that lead to a revolution molecular structure determination using nano-sized crystals is now achieving atomic resolution. structures can be obtained from ED data with tools similar those used for X-ray determination. In this context, the MoPro software, originally designed and charge density refinements data, has been adapted. Structure refinement on was achieved via implementation of scattering factors available literature by...

The multipole model (MM) uses an aspherical approach to describe electron density and can be used interpret data from X-ray diffraction in a more accurate manner than using the spherical approximation. MATTS (multipolar atom types theory statistical clustering) bank gathers MM parameters specific for proteins, nucleic acids, organic molecules. However, it was not fully understood how of particular atoms responds their surroundings which factors molecules within MM. In this work, by applying...

Hirshfeld atom refinement (HAR) is a method which enables the user to obtain more accurate positions of hydrogen atoms bonded light chemical elements using X-ray data. When data quality permits, this can be extended hydrogen-bonded transition metals (TMs), as in hydride complexes. However, addressing thermal motions with HAR, particularly TM hydrides, presents challenge. At same time, proper description vibrations vital for determining correctly. In study, we employ tools such SHADE3 and...

The application of Hirshfeld atom refinement (HAR) fragmentation is demonstrated for the metal–organic framework (MOF) crystal structures.

Two-dimensional diffuse X-ray scattering from an organic salt [N-(3-(2,6-dimethylanilino)-1-methylbut-2-enylidene)-2,6-dimethylanilinium chloride, C21H27N2(+)Cl(-)] was interpreted with the help of analytical model scattering. An analysis relationship between symmetry and for studied system has been undertaken. The explains extinction pattern, taking form curves, on planes. We have also tested average structure intensities. Two models, differing in their representation overlapping atoms,...

Reaching beyond the commonly used spherical atomic electron density model allows one to greatly improve accuracy of hydrogen atom structural parameters derived from X-ray data. However, effects asphericity are less explored for diffraction In this work, Hirshfeld refinement (HAR), a method that uses an accurate description by quantum mechanical calculation system interest, was applied first time kinematical This approach here derive structure ordinary hexagonal ice (I

Hirshfeld atom refinement (HAR) is generally the chosen method for obtaining accurate hydrogen parameters from X-ray diffraction data. Still, determination can prove challenging, especially in case of atomic displacement (ADPs). We demonstrate that such a situation occur when ADP values bonding partner are not determined accurately. Atomic electron densities partially overlap and inaccuracies neighbour ADPs be compensated with modifications to ADPs. introduce modified version original...