Article
Chemistry, Physical
Laurent Lemmens, Xeno De Vriendt, Patrick Bultinck, Guillaume Acke
Summary: In this study, the spin phases and phase transitions during molecular dissociation in the presence of an external uniform magnetic field were explored. It was demonstrated that these spin phases can be interpreted and described by constraining the states to target expectation values of projected spin. The constrained states offer a complete electronic characterization and can be analyzed using standard quantum chemical tools.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Francesco Ferdinando Summa
Summary: This paper presents a derivation of the total induced current density vector field in the presence of static and uniform magnetic and electric fields, using a clearer and formally correct language. It also discusses the charge-current conservation law for the spin-orbit coupling contribution. The theory is consistent with Special Relativity and can be applied to open-shell molecules with nonvanishing spin orbit coupling. The discussion is valid for a strictly central field due to the chosen approximation of the spin-orbit coupling Hamiltonian, but is suitable for accurately dealing with molecular systems. The paper includes maps of spin currents on molecules such as CH3 radical and the superoctazethrene molecule.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Multidisciplinary Sciences
Inbar Seroussi, Gadi Naveh, Zohar Ringel
Summary: Deep neural networks (DNNs) have complex structures, making direct microscopic analysis difficult. However, by identifying slow variables that average the behavior of fast variables, the authors have found a similar scale separation in finite deep convolutional neural networks and fully connected networks. They show that DNN layers couple through the second cumulant of their activations and pre-activations, which fluctuate in a Gaussian manner. The resulting thermodynamic theory of deep learning provides accurate predictions and new ways to understand DNNs.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Zheng Zhang, Hadiah Fattal, Tielyr D. Creason, Mehran Amiri, Alexander Roseborough, Isaiah W. Gilley, May Nyman, Bayram Saparov
Summary: Recently, the solution chemistry of a model indium halide system, methylammonium (MA)-In-Br, was studied using a combination of various techniques. The results showed that under different loading ratios of reactants, indium could form either octahedral or tetrahedral anions in solution, or a combination of both. The understanding of the solution chemistry of this system led to the targeted crystallization of two novel compounds. These findings highlight the importance of understanding the solution chemistry of multinary metal halide systems for the discovery of functional materials for practical applications.
INORGANIC CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Davis Zavickis, Kristians Kacars, Janis Cimurs, Andris Gulans
Summary: This paper presents an implementation of the adaptively compressed exchange (ACE) operator in the linearized-augmented plane waves formalism, and applies it to nonrelativistic total-energy calculations and the calculation of band gaps in solids. The results show that ACE operator, combined with the use of high-energy local orbitals, can achieve high precision in Fock exchange.
Article
Chemistry, Physical
Tanner Culpitt, Laurens D. M. Peters, Erik I. Tellgren, Trygve Helgaker
Summary: The study investigates the properties of the diagonal nonadiabatic term in the Born-Oppenheimer wave function ansatz, deriving analytic expressions for the Berry curvature and DBOC and calculating their properties in several molecules based on magnetic field strength and bond distance. The results indicate that the characteristics of DBOC and Berry curvature vary between molecules and instances of broken time-reversal symmetry are identified in the dissociation curves of BH and CH+.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Jacques K. Desmarais, Alberto Boccuni, Jean-Pierre Flament, Bernard Kirtman, Alessandro Erba
Summary: This article generalizes a previously proposed noncanonical coupled-perturbed Kohn-Sham density functional theory (KS-DFT)/Hartree-Fock (HF) treatment for spin-orbit coupling to infinite periodic systems. The approach is validated and implemented in the CRYSTAL program, and calculations are performed on the tungsten dichalcogenide hexagonal bilayer series. The results show good agreement with reference two-component self-consistent field (2c-SCF) calculations for total energy, electronic band structure, and density variables of spin-current DFT.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Elan D. R. Mistry, Daphne Lubert-Perquel, Irena Nevjestic, Giuseppe Mallia, Pilar Ferrer, Kanak Roy, Georg Held, Tian Tian, Nicholas M. Harrison, Sandrine Heutz, Camille Petit
Summary: A family of boron nitride (BN)-based photocatalysts for solar fuel syntheses have recently emerged. Studies have shown that oxygen doping, leading to boron oxynitride (BNO), can extend light absorption to the visible range. This study demonstrates the importance of paramagnetic isolated OB3 states in inducing red-shifted light absorption and highlights the detrimental effects of diamagnetic O-B-O states on photochemistry in BNO semiconductors. The findings provide fundamental insights into the photophysics of BNO and pave the way for tailoring its optoelectronic and photochemical properties for solar fuel synthesis.
CHEMISTRY OF MATERIALS
(2023)
Review
Chemistry, Physical
Maria Belen Ruiz
Summary: This paper reviews the history of Half-Projected Hartree-Fock theory, provides a compilation of publications on this method, and discusses its extension to the calculation of excited states with the same symmetry.
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
(2022)
Article
Chemistry, Physical
Anish Chakraborty, Rahul Maitra
Summary: The dual exponential coupled cluster theory proposed by Tribedi et al. demonstrates superior performance in dealing with weakly correlated systems compared to the coupled cluster theory with singles and doubles excitations. By including high-rank excitations through vacuum annihilating scattering operators, the theory achieves implicit inclusion of these excitations. However, it is prone to instabilities. This paper shows that restricting the correlated wavefunction to singlet-paired determinants can avoid catastrophic breakdown.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Hayoung Yu, Suhwan Song, Seungsoo Nam, Kieron Burke, Eunji Sim
Summary: This study compares the performance of ROHF and UHF in density functional theory and finds that ROHF can significantly improve energetics in cases of spin contamination, and it enhances the predictive power of DC-DFT in most tested cases.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Physical
Oleg Reu, Serghei Ostrovsky, Sophia Klokishner
Summary: The charge-transfer-induced spin transition of the cyanide-bridged tetranuclear complex [Co2Fe2(bpy*)(4)(CN)(6)(tp*)(2)](PF6)(2)-2CP-8BN has been studied using DFT calculations of single-point energies at various temperatures. The results reveal the spin conversion process of the compound and show that different spin states are present at different temperatures. The findings are consistent with experimental data on magnetic susceptibility, and the potential for predicting spin transitions in new materials based on DFT calculations is discussed.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Materials Science, Multidisciplinary
Tharathep Plienbumrung, Maria Daghofer, Andrzej M. Oles
Summary: Superconductivity in doped NdNiO2 arises from the competition of local symmetries and the impact of realistic values of charge-transfer energy, leading to a different scenario compared to high-T-c cuprates. The results show that correlation effects beyond purely on-site interactions should be considered in obtaining effective two-band models.
Article
Materials Science, Multidisciplinary
William P. Comaskey, Filippo Bodo, Alessandro Erba, Jose L. Mendoza-Cortes, Jacques K. Desmarais
Summary: The spin current density functional theory (SCDFT) is a generalization of standard DFT that is used to study fermionic systems with spin-orbit coupling. This study applies SCDFT to the quantum spin Hall phase and shows an improvement in the description of electronic features compared to DFT. The explicit consideration of spin currents in the electron-electron potential of SCDFT is found to be crucial for the appearance of the Dirac cone during the topological phase transition. Additionally, a simple k center dot p quasidegenerate perturbation theory model is used to rationalize the valence band structure of the system.
Article
Chemistry, Physical
Sheng Chen, Kai Wu, Wei Hu, Jinlong Yang
Summary: In this study, the ACE-ISDF formulation is derived for hybrid functional calculations in unrestricted and noncollinear spin DFT with plane waves and periodic boundary conditions. Improved ACE-ISDF low-rank approximations are proposed to further reduce the computational cost for spin-noncollinear systems. Numerical results demonstrate the efficiency and accuracy of the ACE-ISDF method in investigating the electronic and magnetic properties of periodic magnetic systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Jeroen Danon, Anna Birk Hellenes, Esben Bork Hansen, Lucas Casparis, Andrew P. Higginbotham, Karsten Flensberg
PHYSICAL REVIEW LETTERS
(2020)
Article
Physics, Applied
Jeroen Danon, Anasua Chatterjee, Andras Gyenis, Ferdinand Kuemmeth
Summary: The implementation of large-scale fault-tolerant quantum computers requires integrating millions of physical qubits with low error rates and protecting them from environmental noise. Protective approaches include encoding qubits in global or local decoherence-free subspaces, and in dynamical sweet spots of driven systems.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Ida C. Skogvoll, Jonas Lidal, Jeroen Danon, Akashdeep Kamra
Summary: Researchers theoretically studied a system in which a spin qubit is exchange-coupled to an anisotropic ferromagnet with controllable intrinsic squeezing, finding it capable of realizing the quantum Rabi model and enabling concurrent excitation of three spin qubits coupled to the same magnet, which could facilitate the generation of three-qubit Greenberger-Horne-Zeilinger and related states required for Shor's quantum error-correction code.
PHYSICAL REVIEW APPLIED
(2021)
Article
Materials Science, Multidisciplinary
Jonas Lidal, Jeroen Danon
Summary: In this study, a superconductor-normal-superconductor junction based on a two-dimensional hole gas with additional Rashba spin-orbit coupling is investigated. The dependence of the critical current on the direction and magnitude of an applied in-plane magnetic field is examined. A simple model is presented to systematically explore different parameter regimes and obtain numerical results and analytical expressions for limiting cases. The findings serve as a tool for extracting more information about the detailed spin physics in a two-dimensional hole gas based on a measured pattern of critical currents.
Article
Materials Science, Multidisciplinary
Jorgen Holme Qvist, Jeroen Danon
Summary: This article explores the theoretical connection between the leakage current in a double quantum dot and the underlying spin-orbit interaction in the system. The article also provides an analytic expression for the leakage current and discusses the current expression at low external magnetic field, including the hyperfine coupling effect between hole spins and randomly fluctuating nuclear spins.
Article
Materials Science, Multidisciplinary
Jorgen Holme Qvist, Jeroen Danon
Summary: Qubits encoded in the spin state of heavy holes confined in Si- and Ge-based semiconductor quantum dots show potential for efficient spin-based quantum information processing due to long qubit coherence times and fast spin-orbit-based qubit control. Theoretical investigation of the effective g-tensor and effective mass of heavy holes in two-dimensional systems contributes to understanding optimal points in parameter space for hole-spin qubits. Analytic expressions for the anisotropic g-tensor and corrections for localized holes due to various types of spin-orbit interactions are derived, providing insights into efficient electric control over spin states.
Article
Materials Science, Multidisciplinary
Arnau Sala, Jeroen Danon
Summary: In this study, the detailed line shape of EDSR-induced resonances in the leakage current in the regime of spin blockade is theoretically investigated, connecting different line shapes to the different underlying physical mechanisms that can enable the EDSR. Both numerical and analytical investigations are carried out, producing simple analytic expressions that provide insight into the physics at play. The results offer a means to extract more information about the detailed system parameters of quantum dots hosting spin qubits from an EDSR experiment than just their level structure based on the location of the resonances.
Article
Quantum Science & Technology
Christopher Mittag, Jonne Koski, Matija Karalic, Candice Thomas, Aymeric Tuaz, Anthony T. Hatke, Geoffrey C. Gardner, Michael J. Manfra, Jeroen Danon, Thomas Ihn, Klaus Ensslin
Summary: This study demonstrates the creation of high-quality single and double quantum dots hosted in an InAs two-dimensional electron gas, showing accurate control and observing Kondo effect and singlet-triplet spin blockade. By symmetric design of the quantum well, a spin-orbit length of approximately 5-10 μm is achieved, making InAs a compelling host for fundamental studies of spin qubits. The weak spin-orbit coupling and large Rashba coefficient in InAs potentially open avenues for engineering structures with controllable spin-orbit coupling.
Article
Physics, Multidisciplinary
Kushagra Aggarwal, Andrea Hofmann, Daniel Jirovec, Ivan Prieto, Amir Sammak, Marc Botifoll, Sara Marti-Sanchez, Menno Veldhorst, Jordi Arbiol, Giordano Scappucci, Jeroen Danon, Georgios Katsaros
Summary: In planar germanium, hole gases with high mobilities and strong spin-orbit interaction, combined with electrically tunable g factors, are emerging as a promising platform for creating hybrid superconductor-semiconductor devices. A key challenge is the design of high-quality interfaces and superconducting contacts that are resistant to magnetic fields. By combining aluminum and niobium, the researchers demonstrated transparent low-disordered JoFETs capable of withstanding high magnetic fields, paving the way for exploring topological superconductivity in planar germanium.
PHYSICAL REVIEW RESEARCH
(2021)
Article
Optics
Jonas Lidal, Jeroen Danon
Article
Materials Science, Multidisciplinary
Jorgen Holme Qvist, Jeroen Danon
Article
Physics, Multidisciplinary
Arnau Sala, Jorgen Holme Qvist, Jeroen Danon
PHYSICAL REVIEW RESEARCH
(2020)
Article
Materials Science, Multidisciplinary
Jeroen Danon, Ajit C. Balram, Samuel Sanchez, Mark S. Rudner
Article
Materials Science, Multidisciplinary
V. P. Michal, T. Fujita, T. A. Baart, J. Danon, C. Reichl, W. Wegscheider, L. M. K. Vandersypen, Y. V. Nazarov
Article
Materials Science, Multidisciplinary
Esben Bork Hansen, Jeroen Danon, Karsten Flensberg
