Displacement parameters from density-functional theory and their validation in the experimental charge density of tartaric acid

CrystEngComm ◽  
2021 ◽  
Author(s):  
Damian Mroz ◽  
Ruimin Wang ◽  
Ulli Englert ◽  
Richard Dronskowski
Keyword(s):  
Density Functional Theory ◽  
Charge Density ◽  
Tartaric Acid ◽  
Density Functional ◽  
Harmonic Approximation ◽  
Functional Theory ◽  
Anisotropic Displacement Parameters ◽  
A Charge ◽  
Density Study ◽  
Experimental Charge Density

Advanced theory matches advanced experiment: anisotropic displacement parameters for tartaric acid have been calculated in the quasi-harmonic approximation and determined experimentally based on a charge density study.

scholarly journals On the elusive anti-bayerite structure

2020 ◽  
Author(s):  
Georgios S.E. Antipas
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonds ◽  
Charge Density ◽  
Density Functional ◽  
Hydration Shell ◽  
Isomer Ratio ◽  
Energy Decomposition ◽  
Functional Theory ◽  
Deformation Density ◽  
A Charge

Sequential deprotonation of the Cr3+ hexahydrate in an alkaline environment up to the stage of a charge-neutral active hydroxide was studied via density functional theory. The deprotonation could be characterized as autocatalytic since upon completion of every H-abstraction stage, Cr was found to mediate O-H dissociation in the next stage by pre-conditioning the ligand O atom that contributes the highest 2s density into Cr-4s based molecular orbitals; the latter amounts to a greater Cr-O distance due to increased charge density along the Cr-O axis. A direct effect of such Cr-4s/O-2s mixing is the reduction of electronegativity of the ligand-O atom and a corresponding high Voronoi deformation density (VDD) of the attached ligand-H atoms. Based on bonding energy decomposition, a facial to meridional isomer ratio of between 2:1 and 3:1 was derived as the most probable stereochemical mix of the active hydroxide; the latter forms, by mutual donation and acceptance, six hydrogen bonds with second hydration shell molecules.

scholarly journals Thermodynamics of Uranium Tri-Iodide from Density-Functional Theory

2020 ◽  
Vol 10 (11) ◽  
pp. 3914
Author(s):  
Per Söderlind ◽  
Aurélien Perron ◽  
Emily E. Moore ◽  
Alexander Landa ◽  
Tae Wook Heo
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Heat Capacity ◽  
Density Functional ◽  
Thermodynamic Assessment ◽  
Harmonic Approximation ◽  
Metallic System ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Generalized Gradient Approximation

Density-functional theory (DFT) is employed to investigate the thermodynamic and ground-state properties of bulk uranium tri-iodide, UI3. The theory is fully relativistic and electron correlations, beyond the DFT and generalized gradient approximation, are addressed with orbital polarization. The electronic structure indicates anti-ferromagnetism, in agreement with neutron diffraction, with band gaps and a non-metallic system. Furthermore, the formation energy, atomic volume, crystal structure, and heat capacity are calculated in reasonable agreement with experiments, whereas for the elastic constants experimental data are unavailable for comparison. The thermodynamical properties are modeled within a quasi-harmonic approximation and the heat capacity and Gibbs free energy as functions of temperature agree with available calculation of phase diagram (CALPHAD) thermodynamic assessment of the experimental data.

scholarly journals Higher superconducting transition temperature by breaking the universal pressure relation

2019 ◽  
Vol 116 (6) ◽  
pp. 2004-2008 ◽  
Author(s):  
Liangzi Deng ◽  
Yongping Zheng ◽  
Zheng Wu ◽  
Shuyuan Huyan ◽  
Hung-Cheng Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Temperature ◽  
Transition Temperature ◽  
Density Functional ◽  
High Temperature Superconductors ◽  
Density Functional Theory Calculations ◽  
Universal Relation ◽  
Superconducting Transition ◽  
Functional Theory ◽  
A Charge

By investigating the bulk superconducting state via dc magnetization measurements, we have discovered a common resurgence of the superconducting transition temperatures (Tcs) of the monolayer Bi2Sr2CuO6+δ(Bi2201) and bilayer Bi2Sr2CaCu2O8+δ(Bi2212) to beyond the maximum Tcs (Tc-maxs) predicted by the universal relation between Tcand doping (p) or pressure (P) at higher pressures. The Tcof underdoped Bi2201 initially increases from 9.6 K at ambient to a peak at 23 K at 26 GPa and then drops as expected from the universal Tc-P relation. However, at pressures above 40 GPa, Tcrises rapidly without any sign of saturation up to 30 K at 51 GPa. Similarly, the Tcfor the slightly overdoped Bi2212 increases after passing a broad valley between 20 and 36 GPa and reaches 90 K without any sign of saturation at 56 GPa. We have, therefore, attributed this Tcresurgence to a possible pressure-induced electronic transition in the cuprate compounds due to a charge transfer between the Cu 3dx2−y2and the O 2pbands projected from a hybrid bonding state, leading to an increase of the density of states at the Fermi level, in agreement with our density functional theory calculations. Similar Tc-P behavior has also been reported in the trilayer Br2Sr2Ca2Cu3O10+δ(Bi2223). These observations suggest that higher Tcs than those previously reported for the layered cuprate high-temperature superconductors can be achieved by breaking away from the universal Tc-P relation through the application of higher pressures.

Charge density distribution in aminomethylphosphonic acid

2010 ◽  
Vol 66 (5) ◽  
pp. 559-567 ◽  
Author(s):  
Rafał Janicki ◽  
Przemysław Starynowicz
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Density Functional ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
Functional Theory ◽  
X Ray ◽  
Topological Features ◽  
Aminomethylphosphonic Acid ◽  
Experimental Charge Density

The experimental charge density distribution in aminomethylphosphonic acid has been determined from X-ray diffraction and its topological features have been analyzed. The results have shown that the P—O bonds are highly polarized, moreover the P—OH bond is weaker than the bonds to unprotonated O atoms. These facts have been confirmed by theoretical density functional theory (DFT) calculations, which have shown that the single, strongly polarized bonds within the phosphonate group are modified by hyperconjugation effects.

scholarly journals Experimental and theoretical charge density distribution in Pigment Yellow 101

2015 ◽  
Vol 17 (6) ◽  
pp. 4677-4686 ◽  
Author(s):  
Jonathan J. Du ◽  
Linda Váradi ◽  
Jinlong Tan ◽  
Yiliang Zhao ◽  
Paul W. Groundwater ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Distribution ◽  
Charge Density ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
Functional Theory ◽  
X Ray ◽  
Multipole Refinement

The charge density distribution in 2,2′-dihydroxy-1,1′-naphthalazine (Pigment Yellow 101; P.Y.101) has been determined using high-resolution X-ray diffraction and multipole refinement, along with density functional theory calculations.

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