Article
Chemistry, Physical
Li-Ping Ding, Yun Hao Tiandong, Peng Shao, Yan Tang, Zi-Li Zhao, Haiyan Lu
Summary: Yttrium borides have been studied for their superconducting properties and high chemical stability, but little is known about their mechanical properties and hardness. A new YB6 compound with R3m hexagonal structure was discovered, showing higher stability than the experimental synthesized phase. The calculated Vicker hardness of R3m-YB6 is expected to be 37.0 GPa, indicating its potential as an ultrahard metal, while all stable yttrium borides are found to be metallic.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Yan Zhang, Hua-Xin Chen, Li Duan, Ji-Bin Fan
Summary: The new tetragonal ZrO2 (t-ZrO2-II) has a larger average dielectric constant, higher yield, plastic and fracture strengths, smaller elastic anisotropy leading to less stress concentration and fewer microcracks, indicating that it is a better dielectric and structural material compared to the previously reported t-ZrO2-I.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2021)
Article
Materials Science, Multidisciplinary
Yi Liu, Yuxiang Gong, Yiren Wang, Yong Jiang, Chunlei Shen, Xiaosong Zhou, Xinggui Long
Summary: The surface structures and relative stabilities of low-miller-index surfaces of & gamma;-TiH and & gamma;-TiH2 have been investigated as a direct function of environmental conditions. It was observed that the dominant surface termination of & gamma;-TiH changes with increasing p(H2), while & gamma;-TiH2 is stable only when p(H2) exceeds a certain threshold. The surface phase diagrams and surface energies of & gamma;-TiH and & gamma;-TiH2 were also determined.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Jinquan Zhang, Yuanyuan Jin, Chuanzhao Zhang, Yanqi Wang, Libiao Tang, Song Li, Meng Ju, Jingjing Wang, Weiguo Sun, Xilong Dou
Summary: We present the results of a structure search for iridium borides using calculations and optimization algorithms. We identified the lowest energy crystalline structures as well as three promising metastable phases. The C2/m-Ir3B2 phase was found to have high hardness and compressibility, making it a promising material. The Ir-B compounds showed anisotropic properties, with Ir2B having the highest anisotropy. Additionally, all the iridium borides were found to be ductile.
Article
Metallurgy & Metallurgical Engineering
Sheng Lu, Jianning Zhang, Huajian Wu, Yiren Wang, Yong Jiang
Summary: First-principles energetics calculations and thermodynamic defect model were used to investigate the structures and stabilities of YAlO3 crystal surfaces. The results showed that YAP (100) and (001) had the lowest surface energies, and the surface stabilities of YAP were strongly correlated with its surface stoichiometry.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Chun Gao, Guina Guo, Shuxian Hu, Haitao Liu, Wenli Zou, Ping Zhang, Jun Yan
Summary: In this study, we used a combination of the particle swarming optimization algorithm and the relativistic density functional theory to investigate the geometric structures and stabilities of lead clusters doped with one uranium atom. We found that the structures of the clusters gradually evolved from exohedral to quasi-endohedral and finally endohedral as the number of lead atoms increased. The calculation showed that at least 12 and 11 lead atoms were needed to completely encapsulate the uranium atom without and with the spin-orbit coupling effect, respectively. The UPb16 cluster was identified as a highly stable endohedral cage structure with the uranium atom at its center. The importance of the spin-orbit coupling effect was also emphasized. We hope that our findings will contribute to a better understanding of actinide-doped lead clusters, which may exhibit different behaviors compared to their light element analogues.
MATERIALS TODAY COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Huajian Wu, Jianning Zhang, Yiren Wang, Jiacheng Shang, Yong Jiang
Summary: First-principle total energy calculations were conducted to study the atomic structures and relative stabilities of two low miller-index surfaces of pyrochlore Y2Zr2O7. Stoichiometric Y2Zr2O7 (110) and (100) surfaces were predicted with lowest formation energies of 1.20 and 1.47 J/m(2), respectively. Surface phase diagrams were constructed for T = 300 and 1400 K by evaluating non-stoichiometric Y2Zr2O7 surface energies as a function of environmental oxygen partial pressure (p(O2)) and temperature (T). The results reveal a strong correlation between structural stabilities and surface stoichiometry as the conditions of T and p(O2) vary.
Article
Materials Science, Multidisciplinary
Enda Xiao, Hao Ma, Matthew S. Bryan, Lyuwen Fu, J. Matthew Mann, Barry Winn, Douglas L. Abernathy, Raphael P. Hermann, Amey R. Khanolkar, Cody A. Dennett, David H. Hurley, Michael E. Manley, Chris A. Marianetti
Summary: Phonon lifetimes are crucial in quasiparticle theories of transport, but direct comparisons with inelastic neutron scattering results reveal the importance of accounting for the reciprocal space voxel. Accurate prediction of peak widths of the scattering function when considering the q voxel in CaF2 and ThO2 demonstrates high fidelity in phonon interactions and Green's function calculations, serving as a critical benchmark for theory. This implies that accurately predicting other material properties, as demonstrated for thermal conductivity, is feasible.
Article
Physics, Multidisciplinary
Florian Knoop, Thomas A. R. Purcell, Matthias Scheffler, Christian Carbogno
Summary: In this study, 465 experimentally known materials were classified and fully anharmonic ab initio Green-Kubo calculations were performed for 58 of them. The results revealed 28 thermal insulators, including 6 with ultralow thermal conductivity of only 1 W/mK. The underlying mechanism driving strong anharmonic dynamics was found to be the exploration of metastable intrinsic defect geometries.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Lei Zhang, Jingjing Gu, Xiliang Luo, Zhenyu Tang, Yang Qu, Chenghao Zhang, Han Liu, Jishuai Liu, Congxia Xie, Zhongtao Wu
Summary: A new type of azobenzene-containing surfactant is designed for the fabrication of photoresponsive phase change biomaterials, providing better stability and resistance. The locked cis-azobenzene can be efficiently unlocked by visible light, offering a new approach for designing phase change materials only responsive to light.
Article
Chemistry, Multidisciplinary
Cody J. Perry, Gregory J. O. Beran
Summary: Photomechanical organic crystals can generate mechanical work through solid-state photochemical reactions. This study investigates the influence of substituting hydrogen atoms with fluorine or chlorine at different positions on the photomechanical response, focusing on the [4 + 4] photodimerization of 9-anthracene carboxylic acid. The results reveal that even simple chemical substitutions that maintain the overall crystal packing motif can have unexpected effects on the photochemical response, due to the interplay of intramolecular deformations and intermolecular crystal packing interactions. Additionally, the changes in work density obtained from halogenated species are much smaller compared to changes achieved by varying the crystal packing motif, suggesting that crystal engineering is more effective in increasing the work density of a system.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Chemistry, Physical
Ronald L. Kam, KyuJung Jun, Luis Barroso-Luque, Julia H. Yang, Fengyu Xie, Gerbrand Ceder
Summary: This article investigates the phase diagram of the Li2S-P2S5 pseudo-binary system and finds that the superionic conductors in this system are metastable but thermodynamically accessible at room temperature. The vibrational and configurational entropy play crucial roles in the stability of superionic conductors.
CHEMISTRY OF MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Moumita Naskar, Soumen Ash, Debendra Prasad Panda, Chandan Kumar Vishwakarma, Brajesh Kumar Mani, A. Sundaresan, Ashok Kumar Ganguli
Summary: We report the synthesis and detailed characterization of superconducting La3Se4, and found that it has a high critical temperature and strong-coupling superconductivity. By experimental measurements and theoretical simulations, the superconducting parameters of La3Se4 were determined, and band crossings and band splitting near the Fermi energy due to spin-orbit coupling were observed.
Article
Materials Science, Multidisciplinary
Reo Kita, Masayuki Toyoda, Susumu Saito
Summary: By calculating total energies and free energies, we explored the production of Si polytypes and found that different phases have varying stabilities at different lattice constants. Thermal effects were investigated, revealing that the 2H phase may become as stable as the 3H and 4H phases at higher temperatures. Additionally, the possibility of the homoepitaxial growth of the 4H phase under biaxial stress during high-temperature CVD process was discussed.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Chemistry, Physical
Pandu Wisesa, Christopher M. Andolina, Wissam A. Saidi
Summary: This study accelerates accurate calculations of density functional theory using deep neural network potentials and investigates the melting behavior of MgO under extreme high-pressure conditions. The results show excellent agreement between the predicted melting curve and existing experimental studies. Additionally, the deep neural network potentials successfully describe the metallization of MgO at increased pressures.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Wei Bin How, Bipeng Wang, Weibin Chu, Sergiy M. Kovalenko, Alexandre Tkatchenko, Oleg Prezhdo
Summary: Supervised and unsupervised machine learning techniques were used on descriptors generated from nonadiabatic molecular dynamics (NA-MD) trajectories of CsPbI3 to predict and simulate non-radiative charge recombination, improving the performance of the material.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Alexandre Tkatchenko, Dmitry V. Fedorov
Summary: Quantum electrodynamic fields exhibit fluctuations in the form of particle-antiparticle dipoles, characterized by a nonvanishing polarizability density. In this study, a quantum scaling law is extended to describe the volumetric and radial polarizability density of a quantum field associated with electrons and positrons, and the Casimir self-interaction energy density (E over bar SIE) of the field is derived in terms of the fine-structure constant. The proposed model satisfies the cosmological equation of state w = -1 and the calculated E over bar SIE falls within the range of the recent measurements of the cosmological constant ? obtained by the Planck Mission and the Hubble Space Telescope.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Stefan Chmiela, Valentin Vassilev-Galindo, Oliver T. Unke, Adil Kabylda, Huziel E. Sauceda, Alexandre Tkatchenko, Klaus-Robert Mueller
Summary: We have developed an exact iterative approach to train global symmetric gradient domain machine learning (sGDML) force fields, which can accurately describe complex molecular systems and materials. We evaluated the accuracy and efficiency of sGDML on a newly developed MD22 benchmark dataset containing molecules from 42 to 370 atoms.
Article
Chemistry, Physical
Reabetswe R. Zwane, Joaquin Klug, Sarah Guerin, Damien Thompson, Anthony M. Reilly
Summary: In recent years, computational methods, particularly dispersion-corrected density functional theory (DFT), have been used to predict and design the mechanical response of molecular crystals. The results show that the supramolecular packing, such as extended H-bond or ir-ir networks, plays a crucial role in determining the mechanical behavior of the crystals. This has important implications for drug development.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Multidisciplinary Sciences
Adil Kabylda, Valentin Vassilev-Galindo, Stefan Chmiela, Igor Poltavsky, Alexandre Tkatchenko
Summary: Machine learning force fields (MLFFs) are being optimized to enable molecular dynamics simulations with ab initio accuracy but at a fraction of the computational cost. Challenges remain in developing efficient descriptors for non-local interatomic interactions and reducing dimensionality of descriptors for enhanced applicability and interpretability. An automatized approach is proposed to reduce interatomic descriptor features while maintaining accuracy and efficiency of MLFFs. The results show the importance of non-local features in preserving overall accuracy and reducing the required features to a comparable number with local interatomic features.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Almaz Khabibrakhmanov, Dmitry V. Fedorov, Alexandre Tkatchenko
Summary: This study presents a universal parameterization method for quantum-mechanical van der Waals (vdW) potentials based on two free-atom properties, namely the static dipole polarizability and the dipole-dipole C-6 dispersion coefficient. The derived vdW-QDO potential accurately predicts vdW binding energy curves for noble-gas dimers and exhibits correct asymptotic behavior. It is also shown to accurately describe vdW interactions in dimers consisting of group II elements. The applicability of the atom-in-molecule vdW-QDO model for predicting dispersion energies for molecular systems is demonstrated. This work is an important step toward constructing universal vdW potentials for (bio)molecular computational studies.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Xubin Wang, Shiqi Wang, Jingwen Wang, Shiwei Yin
Summary: This study presents a genetic algorithm (GA) optimization combined with the INDO/CIS method to design TADF molecules. A predefined DA library is used to generate TADF candidates, and the fitness function evaluates their performance. The fitness function considers the emission wavelength, energy gap between S-1 and T-1 excited states, and oscillator strengths for electron transition. The INDO/CIS method is used to quickly calculate the fitness function, and the GA approach is utilized to search for wavelength-specific TADF molecules.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Physical
Szabolcs Goger, Almaz Khabibrakhmanov, Ornella Vaccarelli, Dmitry V. Fedorov, Alexandre Tkatchenko
Summary: The quantum Drude oscillator (QDO) is an efficient coarse-grained approach used to model electronic and optical response properties of atoms and molecules. An optimized parametrization (OQDO) is presented in this study, where the parameters are fixed using only dipolar properties. The OQDO accurately reproduces atomic polarization potentials and multipolar dispersion coefficients for the periodic table of elements and small molecules, showing great potential in the development of next-generation quantum-mechanical force fields for (bio)molecular simulations.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Correction
Multidisciplinary Sciences
Adil Kabylda, Valentin Vassilev-Galindo, Stefan Chmiela, Igor Poltavsky, Alexandre Tkatchenko
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Victor G. Ruiz, Christian Wagner, Friedrich Maass, Hadi H. Arefi, Stephan Stremlau, Petra Tegeder, F. Stefan Tautz, Alexandre Tkatchenko
Summary: The authors accurately characterized the adsorption energy of perylene-tetracarboxylic dianhydride molecules on Au(111) using temperature-programmed desorption, single-molecule atomic force microscopy, and non-local density-functional theory. Studying inorganic/organic hybrid systems is crucial for designing complex interfaces.
COMMUNICATIONS CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Leonardo Medrano Sandonas, Johannes Hoja, Brian G. Ernst, Alvaro Vazquez-Mayagoitia, Robert A. Distasio, Alexandre Tkatchenko
Summary: The rational design of molecules with specific quantum-mechanical properties requires an understanding of the relationships between structure-property and property-property in chemical compound space. In this study, the analysis of a comprehensive dataset revealed a high degree of flexibility in designing molecules with desired properties or a set of distinct molecules with various properties. Using multi-objective optimization, non-trivial paths through chemical compound space were identified that lead to molecules with optimal combinations of polarizabilities and HOMO-LUMO gaps.
Article
Chemistry, Physical
Szabolcs Goger, Leonardo Medrano Sandonas, Carolin Mueller, Alexandre Tkatchenko
Summary: Understanding the correlations - or lack thereof - between molecular properties is crucial for efficient molecular design. This study explores the relationship between electronic structure and chemical properties in molecular systems, specifically the energy gap and dipole polarizability. Through analysis of a comprehensive dataset and molecular composition, it is demonstrated that there is no correlation between polarizability and HOMO-LUMO gap for sufficiently diverse chemical compounds. The lack of correlation allows for the design of novel materials, exemplified by the case of organic photodetector candidates.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Mario Galante, Alexandre Tkatchenko
Summary: The modeling of conformations and dynamics is crucial for understanding the properties of (bio)polymers in soft matter. Noncovalent interactions, rather than short-range interactions, play a dominant role in determining the global conformations. Considering many-body effects in van der Waals (vdW) dispersion has been shown to guide the conformation towards globally optimized structures by reducing the roughness of the energy landscape and promoting global spatial symmetries.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Physics, Multidisciplinary
Matthieu Sarkis, Alessio Fallani, Alexandre Tkatchenko
Summary: Noncovalent interactions play a crucial role in determining the structure, stability, and dynamics of materials, molecules, and biological complexes. However, accurately modeling these interactions on classical computers is challenging. In this study, we demonstrate the potential of the Coulomb-coupled quantum Drude oscillator (cQDO) model for simulating noncovalent interactions on a photonic quantum computer. We calculate the binding energy curve of diatomic systems using Xanadu's STRAWBERRY FIELDS photonics library. Our findings significantly expand the application of quantum computing to atomistic modeling, beyond the standard electronic-structure problem of small molecules. We also propose efficient functional forms for cQDO wave functions that can be optimized on classical computers and capture the bonded-to-noncovalent transition with increasing interatomic distances.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Alex M. Maldonado, Igor Poltavsky, Valentin Vassilev-Galindo, Alexandre Tkatchenko, John A. Keith
Summary: Gradient-domain machine learning (GDML) force fields show excellent accuracy, data efficiency, and applicability for molecules, and a many-body approach opens the possibility of increased transferability to molecular ensembles.
