Article
Chemistry, Physical
Ryosuke Jinnouchi, Ferenc Karsai, Carla Verdi, Georg Kresse
Summary: In this study, a machine learning aided molecular dynamics method is proposed to evaluate the hydration free energy of atoms and molecules adsorbed at liquid-solid interfaces. The calculated hydration free energies indicate that only the hydroxyl group adsorbed on the Pt(111) surface attains a hydration stabilization, which is attributed to differences in the adsorption site and surface morphology.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Multidisciplinary Sciences
Rahul Nikhar, Krzysztof Szalewicz
Summary: Developing theoretical frameworks for predicting new polymorphs is valuable. This study presents an ab initio based force-field approach that significantly speeds up crystal structure prediction compared to fully ab initio schemes. The authors have developed an inexpensive and reliable method for molecular crystal structure predictions. The method starts from a two-dimensional graph of the crystal's monomers and utilizes quantum mechanical calculations to develop an accurate force field for crystal prediction. The robustness of this method has been demonstrated by successfully finding the experimental crystal within the top 20 predicted polymorphs for each molecule investigated.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Yangyang Wan, Xu Zhang, Guillermo C. Bazan, Thuc-Quyen Nguyen, Gang Lu
Summary: This study comprehensively investigates the properties of polarons and bi-polarons in CPEs, including their stability, structural deformation, electronic structure, and optical absorption. The research reveals that these properties depend on the electrostatic interaction between the polarons and ionic functionalities, as well as the combinations of donor and acceptor units in the CPEs backbones. Additionally, the study sheds light on the electrochemical stability of CPEs and discusses strategies to improve it.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Multidisciplinary
Fangzhou Zhao, Mark E. Turiansky, Audrius Alkauskas, Chris G. Van de Walle
Summary: Trap-assisted Auger-Meitner recombination is highlighted as a dominant nonradiative process in wide-band-gap materials, and a first-principles methodology is presented to determine the rates of this process in semiconductors or insulators due to defects or impurities.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Xin Liu, Yang Liu, Hao-Ran Zhu, Xue-Hua Liu, Wen-Li Zhang, Xu Zuo
Summary: This study investigated the effect of stress on the depassivation reactions of interface defects in a-SiO2/Si using molecular dynamics and first-principles calculations. The results show that appropriate interface stress can prolong the depassivation time of defects and extend the service life of devices.
FRONTIERS IN MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Tian-Yu Sun, Yu Hao, Ying-Hao Wu, Wen-Jie Zhao, Liang-Feng Huang
Summary: Ultrathin two-dimensional coatings like graphene and hexagonal boron nitride have attracted attention in the field of corrosion protection for their unique properties, but understanding the microstructure, mechanisms, and interactions with substrates are crucial for their anticorrosion performance, requiring first-principles calculations based on DFT for insight into the microscopic mechanisms.
Article
Chemistry, Physical
Liucheng Liu, Shengfeng Zhou, Haoran Gong
Summary: This study comparatively examines the hydrogen behavior at PdCu(110)-Mo2C(001) interfaces using first principles calculations. It is found that adding Mo2C as a coating and support can increase the hydrogen solubility of a BCC PdCu membrane. However, the formation of PdCu(110)-Mo2C(001) interfaces hinders hydrogen diffusion. The results provide insights into the effects of interface formation on hydrogen behaviors and suggest Mo2C/PdCu composite membranes as promising candidates for hydrogen permeation.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Review
Physics, Condensed Matter
Derek Dardzinski, Maituo Yu, Saeed Moayedpour, Noa Marom
Summary: Interfaces between materials can achieve properties and functionalities that are not present in either material alone. First principles simulations based on density functional theory (DFT) can elucidate the electronic and magnetic properties of interfaces and predict the structure and properties of candidate interfaces. However, simulations of interfaces can be complex and computationally expensive.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Materials Science, Multidisciplinary
David G. Gonzalez, Gaoxue Wang, Ping Yang, Enrique R. Batista
Summary: Research on the complex polar oxide heterojunction of SrTiO3/LaAlO3 (STO/LAO) on the three crystallographic planes indicates that the main mechanism for conductivity in the 110 and 111 planes is attributed to large structure reconstruction causing local energy level changes.
Article
Chemistry, Physical
Zhihao Li, Xiucai Sun, Xiaoli Sun, Wan-Jian Yin, Zhongfan Liu
Summary: This study investigated the impact of substrate characteristics on the quality of graphene and found that the crystallographic orientation of the metal substrate, such as Cu (100), is crucial for producing high-quality and superclean graphene. The study also identified that low graphene defect density and high nucleation rate on the Cu(100) facet contribute to the suppression of amorphous carbon formation and facilitate rapid graphene synthesis.
Article
Physics, Multidisciplinary
Malik Wagih, Christopher A. Schuh
Summary: The segregation of solute atoms at grain boundaries significantly affects the properties of polycrystals. However, there is a limited understanding of the variations in solute segregation tendencies in different grain boundary microenvironments and a wide range of alloys. This study presents an algorithmic framework that can learn the complete spectrum of solute segregation energies in metal polycrystals without the need for alloy interatomic potentials. It offers a pathway to comprehensively catalog grain boundary solute segregation with quantum accuracy for all alloy compositions.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Zhuo-Ni Dai, Ying Xu, Dai Feng Zou, Wen Jin Yin, Jun Nian Wang
Summary: In this paper, we designed InN/XS2 (X = Zr, Hf) heterojunctions and systematically studied their electronic structure, photocatalytic performance, and light absorption using first-principles calculations. We found that the valence-band maximum and conduction-band minimum of the heterojunctions are contributed by InN and XS2, respectively. The photogenerated carriers along the Z-path facilitate the recombination of interlayer electron-hole pairs, enabling continuous hydrogen and oxygen evolution reactions. Transition metal doping can tune the hydrogen evolution reaction barriers, and the optical absorption coefficient is high in the visible and ultraviolet regions. Therefore, the InN/XS2 heterojunctions are expected to be excellent photocatalysts for water splitting.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Tamas Szidarovszky
Summary: A theoretical framework is proposed for calculating the rovibrational polaritonic states of a molecule in an infrared microcavity. The rotational and vibrational motions of the molecule are treated quantum mechanically using arbitrary approximations. Changes in electronic structure induced by the cavity are treated perturbatively, making use of standard quantum chemistry tools. The study shows that the self-dipole interaction and molecular polarizability are important for accurate energy level shifts induced by the cavity, while the magnitude of polarization remains small, justifying the perturbative approach.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Jingtao Huang, Mingwei Li, Jiaying Chen, Yuan Cheng, Zhonghong Lai, Jin Hu, Fei Zhou, Nan Qu, Yong Liu, Jingchuan Zhu
Summary: Based on density functional theory, this study investigates the diffusion migration behavior of alloy atoms in the aluminum matrix and the graphene/aluminum interface. It is found that aluminum atoms prefer to migrate towards the interface to facilitate the formation of the brittle phase Al4C3. The diffusion migration behaviors of 41 alloying atoms are calculated, and a group of alloying elements that tend to aggregate at the interface are identified. Furthermore, the migration behavior of alloying atoms at the graphene/aluminum interface with a carbon atom vacancy defect is explored.
SURFACES AND INTERFACES
(2023)
Article
Chemistry, Physical
Michael W. Swift, John L. Lyons
Summary: This study evaluates various potential acceptor dopants for p-type doping in all-inorganic lead halide perovskites, such as cesium lead bromide, using first-principles calculations. The research shows that the difficulty of achieving p-type doping in these materials is due to moderately high formation energies of acceptor impurities and compensation from native defects. Sodium and silver are identified as the most promising dopants for overcoming these challenges, and optimum chemical potential conditions for acceptor doping are determined.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Abhishek Shandilya, Kathleen Schwarz, Ravishankar Sundararaman
Summary: Understanding the charging behavior and thermodynamics of the electrochemical interface is crucial for controlling electrochemical reactivity. This study combines classical molecular dynamics simulations with charge response from electronic density functional theory to predict the potential-dependent capacitance of ideal aqueous electrochemical interfaces. The results show a range of electrode charge of maximum capacitance (-2.9 to -2.2 mu C/cm(2)) regardless of the details in the electronic response. The study also reveals asymmetric response of interfacial water for negatively charged electrodes and a peak entropy charge of -5.1 ± 0.6 mu C/cm(2).
JOURNAL OF CHEMICAL PHYSICS
(2022)
Review
Chemistry, Multidisciplinary
Ravishankar Sundararaman, Derek Vigil-Fowler, Kathleen Schwarz
Summary: Atomistic simulation of the electrochemical double layer is a complex task that requires quantum mechanical description of electrons, phase space sampling of liquid electrolytes, and equilibration of electrolytes over nanosecond time scales. Different models of electrochemistry make different compromises in the approximation of electrons and atomic configurations. This review discusses various simulation techniques suitable for electrochemistry, emphasizing the key approximations and accuracy considerations for each technique. Promising approaches, such as enhanced sampling techniques for atomic configurations and computationally efficient electronic methods beyond density functional theory (DFT), are also explored, which will push the boundaries of electrochemical simulations.
Correction
Chemistry, Physical
Abhishek Shandilya, Kathleen Schwarz, Ravishankar Sundararaman
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Hung M. Le, Sushant Kumar, Nathan May, Ernesto Martinez-Baez, Ravishankar Sundararaman, Bala Krishnamoorthy, Aurora E. Clark
Summary: Identifying collective variables (CVs) for chemical reactions is crucial but challenging due to the nonmeaningful motions of bulk solvent. This work proposes a distance-attenuated projection method that enables both PCA and UMAP to accurately identify CVs in the presence of explicit solvent and determine the specific importance of solvent molecules in chemical reactions.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Optics
Lifu Zhang, Jie Jiang, Christian Multunas, Chen Ming, Zhizhong Chen, Yang Hu, Zonghuan Lu, Saloni Pendse, Ru Jia, Mani Chandra, Yi-Yang Sun, Toh-Ming Lu, Yuan Ping, Ravishankar Sundararaman, Jian Shi
Summary: Researchers demonstrate a persistent spin helix in an organic-inorganic hybrid ferroelectric halide perovskite. They show that the spin-polarized band structure can be switched via an intrinsic ferroelectric field. This discovery has the potential to resolve the control-relaxation dilemma in spintronic devices.
Article
Materials Science, Multidisciplinary
Sushant Kumar, Christian Multunas, Benjamin Defay, Daniel Gall, Ravishankar Sundararaman
Summary: Increasing resistivity of metal wires with reducing nanoscale dimensions is a major performance bottleneck of semiconductor computing technologies. Metals with anisotropic Fermi velocity distributions can effectively suppress electron scattering by surfaces and outperform isotropic conductors. Certain intermetallics and borides with anisotropic Fermi velocities show the most promising performance for narrow wires.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Physics, Applied
Minghua Zhang, Sushant Kumar, Ravishankar Sundararaman, Daniel Gall
Summary: The resistivity size effect in the ordered intermetallic CuTi compound was quantified using in situ and ex situ thin film resistivity measurements, as well as density functional theory calculations. The results showed that the measured resistivity and electron mean free path were in agreement with theoretical calculations, but the measured resistivity mean free path product was almost 2.4 times larger than predicted, indicating a breakdown of classical transport models.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Sushant Kumar, Christian Multunas, Ravishankar Sundararaman
Summary: Directional conductors show significant advantages for efficient hot carrier harvesting. Filmlike conductors PtCoO2 and Cr2AlC have optical response resembling 2D metals, while wirelike conductors CoSn and YCo3B2 resemble 1D metals, enabling efficient light collection in small dimensions.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Ravishankar Sundararaman, Kathleen Schwarz
Summary: Fully harnessing electrochemical interfaces for reactions requires understanding the impact of solvents on properties of the electrochemical double layer. Using molecular dynamics simulations, we show that changing the solvent can switch the signs of the charge of maximum capacitance and charge of maximum entropy at the interfaces. We demonstrate that the preferred orientation of solvent molecules and corresponding charge density determine the charge asymmetry of the electrochemical interface.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Michael Woodcox, Avik Mahata, Aaron Hagerstrom, Angela Stelson, Chris Muzny, Ravishankar Sundararaman, Kathleen Schwarz
Summary: We present a method for computing the dielectric spectra of fluids in molecular dynamics (MD) simulations by directly applying electric fields. We obtain spectra from MD simulations with low magnitude electric fields (approximately 0.01 V/angstrom) that agree with spectra from the fluctuation-dissipation method for water and acetonitrile. We investigate the trade-off between noise and nonlinearity in the response of fluids at different field magnitudes.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Applied
Ganpati Ramanath, Collin Rowe, Geetu Sharma, Venkat Venkataramani, Johan G. Alauzun, Ravishankar Sundararaman, Pawel Keblinski, Davide G. Sangiovanni, Per Eklund, Henrik Pedersen
Summary: Advances in interface science have shown the importance of using molecular nanolayers (MNLs) at inorganic interfaces to enhance interfacial properties. This study captures the ways MNLs induce enhancements and tune multiple properties, such as chemical stability, thermal and electrical transport, and electronic structure. Key challenges for the field's progress are discussed. MNL-induced interfacial engineering offers attractive opportunities for designing organic-inorganic hybrid nanomaterials with high interface fractions.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Prajakta Prabhune, Yigitcan Comlek, Abhishek Shandilya, Ravishankar Sundararaman, Linda S. Schadler, Lynda Catherine Brinson, Wei Chen
Summary: Polymer nanodielectrics pose a challenge in materials design for polymer film capacitors due to the need for high permittivity and breakdown strength while minimizing loss. This study explores a parameter space using simulations and machine learning to optimize these properties by modifying the fillers with charge-trapping molecules. The proposed design framework considers microstructure and interface properties to achieve multiple property optimizations in nanodielectrics.
Article
Chemistry, Physical
Fatemeh Kiani, Alan R. Bowman, Milad Sabzehparvar, Can O. Karaman, Ravishankar Sundararaman, Giulia Tagliabue
Summary: This study reveals the complex interdependence among plasmon excitation, hot-carrier generation, transport, and interfacial collection in plasmonic photocatalytic devices, providing new guidelines for optimizing photocatalytic systems and optoelectronic devices.
ACS ENERGY LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Praveen Gupta, Eric Ruzicka, Brian C. Benicewicz, Ravishankar Sundararaman, Linda S. Schadler
Summary: This paper demonstrates a combined EFM and machine learning approach to measuring interfacial permittivity in polymer nanocomposites. ML models trained with finite-element simulations accurately determine the interface permittivity of functionalized nanoparticles. The approach fully accounts for the complex interplay of filler, matrix, and interface permittivity, providing a pathway to quantify and design nanoscale interface dielectric properties in nanodielectric materials.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Adela Habib, Junqing Xu, Yuan Ping, Ravishankar Sundararaman
Summary: This study uses first-principles density-matrix dynamics simulations to investigate the effect of electric fields and substrates on spin relaxation in graphene. The results show that the interaction with electric fields and substrates significantly enhances spin relaxation through scattering with phonons. The findings have important implications for the development of graphene-based spin technologies at room temperature.