Article
Crystallography
Katarina Stare, Jernej Stare, Sreco Davor Skapin, Matjaz Spreitzer, Anton Meden
Summary: This study focuses on the structural characterization of the solid solution La3-xTi5-3xNb10-2xO39.5-12.5x with x = 0.04 in the ternary system La2O3-TiO2-Nb2O5. The crystal structure was determined using synchrotron and neutron powder diffraction data, revealing a new structural type. The octahedrally coordinated titanium and niobium atoms are disordered in five different crystallographic sites, while the La atoms are embedded in the octahedral framework. The theoretical calculations based on density functional theory agree well with the experimental data, validating its reliability as a complementary tool for structural investigation of ceramic materials.
Article
Chemistry, Physical
Yunxia Wang, Fayan Zhu, Toshio Yamaguchi, Koji Yoshida, Guangguo Wang, Ruirui Liu, Lulu Song, Yongquan Zhou, Hongyan Liu
Summary: Calcium nitrate tetrahydrate shows potential prospects as a room temperature phase change material due to its appropriate melting point and high enthalpy. However, the supercooling problem hinders its widespread use in energy storage. In this study, the microscopic structure of liquid calcium nitrate tetrahydrate at different temperatures is examined using X-ray diffraction and Raman spectroscopy. The results are compared with the crystalline structure of calcium nitrate tetrahydrate. It is found that the structure of the liquid state differs from that of the solid state, with the nitrate ions acting as dioxygen bridges in the liquid state and forming longer chains or shorter ring structures. The findings provide a theoretical basis for addressing the supercooling problem.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Multidisciplinary
Ola G. Grendal, Donald M. Evans, Solveig S. Aamlid
Summary: This study revisits the structures and phase transitions of Ba2NaNb5O15 (BNN) using high-resolution X-ray and neutron powder diffraction combined with density functional theory calculations. The results show that BNN has an average structure described by the Ama2 space group, and no other structural phase transitions were observed. Symmetry mode analysis reveals significant octahedral tilting and corrugations, and a strong correlation between spontaneous strain and octahedral tilting was observed.
JOURNAL OF APPLIED CRYSTALLOGRAPHY
(2023)
Article
Crystallography
Bernhard Massani, Ciprian G. Pruteanu, Lewis J. Conway, Victor N. Robinson, Andreas Hermann, John S. Loveday
Summary: This manuscript presents a neutron powder diffraction study on the structure of ammonia monohydrate IV at high pressure, providing insights into the ammonia-water phase diagram.
Article
Computer Science, Artificial Intelligence
Johannes Gedeon, Jonathan Schmidt, Matthew J. P. Hodgson, Jack Wetherell, Carlos L. Benavides-Riveros, Miguel A. L. Marques
Summary: This article presents a solution to the problems in density functional theory, namely the explicit dependency of the functionals on the particle number and the derivative discontinuity at integer particle numbers. They propose training a neural network as a universal functional that exhibits piece-wise linearity between integer particle numbers and reproduces the derivative discontinuity of the exchange-correlation energy.
MACHINE LEARNING-SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Environmental
Ning Xie, Haiming Wang, Changfu You
Summary: In this study, the adsorption mechanism of Pb2+ on carbonaceous surfaces modified with oxygen functional groups was investigated using density functional theory. It was found that the introduction of oxygen functional groups significantly enhanced the adsorption of Pb2+ on the armchair surface, changing the adsorption mechanism from physisorption to chemisorption.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
Article
Chemistry, Physical
Chunlan Li, Wensheng Liu, Juan Wang, Shuwei Yao, Yunzhu Ma
Summary: In this study, density functional theory was applied to investigate the reaction of Al powder with formic and acetic acid in aqueous solution, revealing the structure of Al(III) complexes. It was found that aluminum hydrates preferentially coordinated with water molecules to form aluminum formoacetate and other aluminum carboxylate monomers. The formation of other aluminum carboxylate monomers significantly influenced the structure of precursor sols.
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
(2021)
Article
Engineering, Chemical
Jianxiong Kang, Yanni An, Jiwei Xue, Xiao Ma, Jiuzhou Li, Fanfan Chen, Sen Wang, He Wan, Chonghui Zhang, Xianzhong Bu
Summary: The electronic structure of the galena surface was investigated using first-principle calculation. The results showed that galena is a p-type semiconductor with a direct band gap. During the formation of galena, the 3p orbital of S and the 6p orbital of Pb played a primary role. Additionally, the surface properties of galena were influenced by the transfer of electrons from the 6p orbital of Pb to the 3p orbital of S.
Article
Materials Science, Multidisciplinary
Prashant Singh, Tyler Del Rose, Guillermo Vazquez, Raymundo Arroyave, Yaroslav Mudryk
Summary: In this study, a descriptor-based machine-learning approach was employed to assess the effect of chemical alloying on the formation enthalpy of rare-earth intermetallics. A rare-earth database was developed using high-throughput density-functional theory (DFT) with more than 600 compounds. The machine-learning method based on SISSO was used to train and test the formation enthalpies, and the complex lattice function was used to investigate the effect of transition metal alloying on energy stability. The study provides quantitative guidance for compositional considerations and facilitates the discovery of new metastable materials.
Article
Chemistry, Physical
Cheng Cai, Weiqiang Tang, Chongzhi Qiao, Bo Bao, Peng Xie, Shuangliang Zhao, Honglai Liu
Summary: This article investigates the solvent effects on nucleophilic addition reactions in aqueous solution using the proposed multiscale reaction density functional theory (RxDFT) method. The results provide a better understanding of the mechanism and the solvent effect on chemical reactions, especially those occurring at solid-liquid interfaces.
GREEN ENERGY & ENVIRONMENT
(2022)
Article
Chemistry, Inorganic & Nuclear
Alex J. Brown, Maxim Avdeev, Alicia Manjon-Sanz, Helen E. A. Brand, Chris D. Ling
Summary: Oxygen-deficient perovskite compounds with the formula Ba3RFe2O7.5 were studied to investigate magnetic interactions between Fe3+ 3d cations with and without unpaired 4f electrons on R3+ cations. The magnetic ground states were determined for R3+ = Y3+ (non-magnetic) and Dy3+ (4f9) using neutron powder diffraction data analysis and ab initio density functional theory calculations. Both compounds exhibited complex long-range ordered antiferromagnetic structures with the same magnetic space group Ca2/c (BNS #15.91) below TN = 6.6 and 14.5 K, respectively. The influence of f-electron magnetism was evident in temperature dependence and differences in ordered moment sizes on the Fe sites.
INORGANIC CHEMISTRY
(2023)
Review
Crystallography
Vladimir V. Chernyshev
Summary: X-ray powder diffraction is a crucial tool in pharmaceutical science, particularly for determining the crystal structure of new pharmaceutical substances. This article discusses the reliability of structural parameters obtained from powder patterns and presents recent examples of successfully determining crystal structures of pharmaceutical cocrystals and salts using powder diffraction data. These examples demonstrate the enhanced capabilities of laboratory X-ray powder diffractometers and modern software in addressing real-life challenges in pharmaceutical science.
Article
Chemistry, Multidisciplinary
Meiyi Jiang, Kun Yang, Hongjing Yu, Li Yao
Summary: Through density functional theory calculations, the effects of different metal oxides adsorbed on the anatase TiO2 (101) surface were studied, indicating that a small amount of CuO increases the reactivity of the catalyst, but the overall catalytic effect is inferior to those with FeO or MnO. Catalysts containing FeO are more stable than those with only CuO or MnO, with higher FeO adsorption ratio leading to increased stability of the catalyst structure.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2021)
Article
Physics, Multidisciplinary
Tomasz Maciazek
Summary: The reduced density matrix functional theory is a powerful tool for studying properties of ground states of strongly interacting quantum many body systems, especially Bose-Einstein condensation and systems of strongly correlated electrons. It has been shown that the density functional in these systems exhibits a repulsive gradient, known as the Bose-Einstein condensation force, which is universal for different types of pair-interaction and non-homogeneous gases. The theory has also been extended to fermionic systems, showing the existence of a similar repulsive gradient in the fermionic RDMFT.
NEW JOURNAL OF PHYSICS
(2021)
Article
Pharmacology & Pharmacy
Devang Patel, Vivek D. Patel, Robert Sedlock, Rahul Haware
Summary: This paper proposes a new approach to using pycnometric tablet density in the relative density calculations of Heckel analysis, which solves the problem of negative porosity in high-pressure regions. The new approach enables the evaluation of macroscopic compaction performance and saves time and costs.
INTERNATIONAL JOURNAL OF PHARMACEUTICS
(2022)
