Article
Green & Sustainable Science & Technology
Nicolas Faedo, Ulises Bussi, Yerai Pena-Sanchez, Christian Windt, John Ringwood
Summary: This article introduces a simple and effective wave excitation force estimator for wave energy converters (WECs), without the need for an explicit model of the input. By formulating the unknown-input estimation problem as a tracking control-loop, a variety of linear time-invariant (LTI) design techniques can be used to compute an estimate of the excitation force. The proposed observer is demonstrated to have superior performance, simplicity, and intuitive appeal through a case study based on realistic computational fluid dynamics simulation, comparing it against a large set of WEC observers.
IEEE TRANSACTIONS ON SUSTAINABLE ENERGY
(2022)
Article
Chemistry, Physical
Joseph A. Weatherby, Adrian F. Rumson, Alastair J. A. Price, Alberto Otero de la Roza, Erin R. Johnson
Summary: Vibrational contributions to the free energy play an important role in determining the stability rankings of crystal candidates. Approximate methods for calculating the vibrational free-energy corrections may have larger errors compared to exact methods, making them less reliable in crystal structure prediction protocols.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Prasanta Bandyopadhyay, Priya, Mainak Sadhukhan
Summary: This paper presents a simple yet effective method for describing intermolecular van der Waals interactions. By combining atom-centered quantum Drude oscillators with the fragmentation of molecular systems, this method reduces the number of parameters compared to traditional methods while maintaining accuracy.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
F. T. Brandt, J. Frenkel, D. G. C. McKeon, G. S. S. Sakoda
Summary: We examine the nonrenormalizability induced by low-energy effective Lagrangians in loop diagrams in a finite scalar model. The mechanism leading to the nonrenormalizability of the effective theory can be demonstrated directly in this framework. While approximations applicable at low energies may generate this behavior, we show that the results obtained in the renormalized effective theory can be matched with those in the full theory at low energy. We argue that the infrared sectors of these theories are inherently similar, independent of the matching procedure.
Article
Mathematics, Interdisciplinary Applications
Meng Xu, Pengjian Shang, Sheng Zhang
Summary: BCDDE is introduced as a method for quantifying complex behavior of dynamical systems, which can describe dynamic characteristics of time series and distinguish different classes of time series. Experimental results show that BCDDE has a significant effect on classifying financial time series.
CHAOS SOLITONS & FRACTALS
(2021)
Article
Engineering, Electrical & Electronic
Filippo Costa
Summary: This study presents a simple and accurate method for computing the effective permittivity of metasurfaces embedded within arbitrary stratified media. The model provides accurate estimation for stackups with several dielectric layers of arbitrary thickness and permittivity. The accuracy of the model is rigorously verified by comparing the estimated effective permittivity with full-wave MoM simulations.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2021)
Article
Astronomy & Astrophysics
Jose F. Nieves, Sarira Sahu
Summary: This article discusses the propagation and interaction of neutrinos and antineutrinos in a medium composed of fermions and scalars. The study focuses on the resonance energy range where the neutrino self-energy exhibits a singularity. The real and imaginary parts of the self-energy are calculated using principal value of integrals and damping effects are taken into account. The article provides explicit formulas for the effective potential and damping coefficient, which are applicable in the resonance energy range as well. The obtained formulas are applied to a simple two-generation case to illustrate their possible applications.
Article
Energy & Fuels
Bilal Taghezouit, Fouzi Harrou, Ying Sun, Amar Hadj Arab, Cherif Larbes
Summary: An effective monitoring method for photovoltaic systems based on parametric models and double exponentially smoothing scheme is designed in this study, successfully detecting various faults through a combination of empirical models and smoothing strategies.
Article
Energy & Fuels
Sofiane Kichou, Tom Markvart, Petr Wolf, Santiago Silvestre, Aissa Chouder
Summary: The use of electrical energy storage is crucial in the transition towards renewable energy sources. Sizing the storage systems effectively is important to manage the volatility of renewable energy and ensure a reliable energy supply. This paper presents a methodology for determining the minimum required size of the storage system and validates it using measurement data from different systems.
JOURNAL OF ENERGY STORAGE
(2022)
Article
Astronomy & Astrophysics
Astrid Eichhorn, Martin Pauly
Summary: This research suggests a direct link between the nature of dark matter and the fundamental quantum structure of spacetime in the asymptotic-safety framework. A toy model for the visible Higgs-Yukawa sector of the Standard Model, coupled to a dark sector through a portal coupling, illustrates the potential for the model to become asymptotically safe, have enhanced predictive power, and predict calculable values for all interactions.
Article
Chemistry, Multidisciplinary
Raj Roy, Abhisek Ghosal, Amlan K. Roy
Summary: In this study, an alternative DFT scheme for calculating lowest single-particle excitation energy in organic chromophores is proposed. The method, based on virial-theorem and 2e- integral evaluation, shows comparable accuracy to TDDFT in predicting vertical excitation energies in small molecules and large polycyclic aromatic hydrocarbons. The functional dependency of the method on three different functionals is explored, demonstrating its validity and usefulness in determining optical gap with fair computational cost.
CHEMISTRY-AN ASIAN JOURNAL
(2021)
Article
Chemistry, Physical
Francois Mairesse, Benoit Champagne
Summary: The quantum treatment of electrons at the Kohn-Sham Density Functional Theory (DFT) level of approximation is used to optimize the structure of four organic and organo-metallic crystalline systems with nonlinear optical properties. The study addresses the lack of London-type interactions description in exchange-correlation functionals (XCFs) by employing the D* scheme, a variation of the D2 correction scaled for crystal solid state interactions. The performance and suitable scaling factors of the D* scheme are demonstrated for four representative XCFs.
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Pengfei Suo, Li Mao, Jing Shi, Hongxing Xu
Summary: Graphite/graphene intercalation compounds are widely used in various applications and possess excellent electrical transport properties, optical properties, magnetic properties, and even superconductivity. Computational simulation helps predict important properties and explore unknown functions, albeit with limitations in computing resources and precision. This study presents a cost-effective simulation method to study the properties of graphite/graphene intercalation compounds with sufficient precision, demonstrating good agreement with previous experimental and calculation work.
Article
Clinical Neurology
Nathan Todnem, Khoi D. Nguyen, Vamsi Reddy, Dayton Grogan, Taylor Waitt, Cargill H. Alleyne
Summary: The study introduces a cost-effective and easy-to-make brain model constructed of homemade ballistics gelatin for teaching and practicing ventricular catheter placement in a risk-free environment. Participants found the brain model easy to use, helpful in understanding EVD placement techniques, and providing good feedback on catheter positioning. All participants achieved adequate catheter positioning after just one attempt.
JOURNAL OF NEUROSURGERY
(2021)
Article
Engineering, Multidisciplinary
Zhong-Rong Lu, Zhiyi Yin, Junxian Zhou, Jike Liu, Li Wang
Summary: A new Measurement-Changes-Correction strategy is proposed to alleviate the undesired effects of model errors on damage identification. This strategy performs well under small aleatoric and epistemic model errors, with almost half the computation cost of the conventional two-step strategy.
STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL
(2021)
Article
Multidisciplinary Sciences
Rachel Garrick, Leeor Kronik, Tim Gould
Summary: A generalized adiabatic connection for any type of range-separated hybrid functional employed within generalized Kohn-Sham theory is presented, which allows for a rigorous distinction between multiplicative exchange and correlation components. The connection is defined in terms of both generalized and conventional KS orbitals, although using only the KS orbitals introduces a small error in practical calculations. The new adiabatic connection is expected to assist in the development and assessment of RSH functionals.
ADVANCED THEORY AND SIMULATIONS
(2022)
Article
Chemistry, Physical
Tim Gould, Zahed Hashimi, Leeor Kronik, Stephen G. Dale
Summary: In this paper, a simple correction method based on rigorous ensemble density functional theory is introduced, which makes the HOMO-LUMO gap exact in principle and significantly improves accuracy in practice. The method predicts different values for singlet-singlet and singlet-triplet excitations, and the quality of excitation energies is similar to time-dependent density functional theory.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Meng Li, Zhenzhen Wu, Mengting Zheng, Hao Chen, Tim Gould, Shanqing Zhang
Summary: Electrochromic materials have the potential to save energy by tuning the illumination and heat exchange between buildings and the environment. In this study, a series of transition metal benzenehexathiol coordination nanosheets (TM-BHT CONASHs) were investigated. The results show that Cu-BHT and Ag-BHT are the most promising broadband electrochromic materials.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Physical
Meng Li, Zhenzhen Wu, Yuhui Tian, Feng Pan, Shanqing Zhang, Tim Gould
Summary: Due to its mechanical flexibility and strength, two-dimensional materials are ideal for strain engineering. It has been found that strain affects the electronic properties and mechanochromic performance of Cu-BHT, indicating its great potential in various applications.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Matteo Ricci, Pier Luigi Silvestrelli, John F. Dobson, Alberto Ambrosetti
Summary: This paper presents an exact theoretical framework for polarizability and asymptotic van der Waals correlation energy functionals of small isolated objects using a sum-rule approach. The functionals only require monomer ground-state properties as input and can be evaluated through a single position-space differential equation. Comparison to popular density functionals shows the best performance when density decay occurs at atomic scales.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Review
Materials Science, Multidisciplinary
Meng Li, Zhenzhen Wu, Yuhui Tian, Feng Pan, Tim Gould, Shanqing Zhang
Summary: This review highlights the recent achievements of emerging 2D electrochromic materials, such as covalent organic frameworks, coordination nanosheets, and transition metal carbides/nitrides/carbonitrides (MXenes). The structures, electrochromic performances, their structure-performance relationship, and future challenges of these materials have been systematically explored. This review opens up new avenues for the practical electrochromic applications of nanoarchitectonic 2D materials.
ADVANCED MATERIALS TECHNOLOGIES
(2023)
Article
Chemistry, Physical
Tim Gould
Summary: Kohn-Sham (KS) inversion sheds light on the nature of exact density functional theory (DFT) and aids in the development of density functional approximations. However, KS inversion remains challenging, especially in finite basis sets. This study introduces a numerically efficient KS inversion method, called the Lieb-response approach, which works well with existing Fock-matrix DFT infrastructure in finite basis sets and provides meaningful matrix and energy quantities for pure-state and ensemble systems. The method enables inversion of even difficult KS systems and offers outputs that can be used for embedding schemes or machine learning of density functional approximations. The impact of finite basis sets on KS inversion is also analyzed and investigated.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Tim Gould, Derk P. Kooi, Paola Gori-Giorgi, Stefano Pittalis
Summary: Density functional theory (DFT) has greatly expanded our ability to compute and understand electronic ground states. However, the treatment of excited states lags behind. In this study, a generalization of density functional theory to ensemble states (EDFT) is proposed to address this problem. The results provide foundations for effective models of excited states that interpolate between exact low-and high-density limits.
PHYSICAL REVIEW LETTERS
(2023)
Article
Chemistry, Physical
Tim Gould
Summary: Approximations based on density functional theory have been dominant in electronic structure theory calculations since the 1990s. Although modern approximations can provide accurate energy differences, the assessment of density quality has received less attention due to the lack of reliable error measures. This work introduces the mean-field error, which directly evaluates the quality of densities from approximations.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Optics
Mojdeh Banafsheh, Tomasz A. Wesolowski, Tim Gould, Leeor Kronik, David A. Strubbe
Summary: This article analyzes the existence of singularities in the nonadditive kinetic potential vNAD for various choices of electron densities, showing that no singularities arise from smoothly partitioned ground-state Kohn-Sham densities. The findings are confirmed through numerical calculations on diatomic test systems, providing insights for the development and testing of approximations to vNAD and kinetic-energy functionals.
Article
Chemistry, Physical
Andrew M. Teale, Trygve Helgaker, Andreas Savin, Carlo Adamo, Balint Aradi, Alexei Arbuznikov, Paul W. Ayers, Evert Jan Baerends, Vincenzo Barone, Patrizia Calaminici, Eric Cances, Emily A. Carter, Pratim Kumar Chattaraj, Henry Chermette, Ilaria Ciofini, T. Daniel Crawford, Frank De Proft, John F. Dobson, Claudia Draxl, Thomas Frauenheim, Emmanuel Fromager, Patricio Fuentealba, Laura Gagliardi, Giulia Galli, Jiali Gao, Paul Geerlings, Nikitas Gidopoulos, Peter M. W. Gill, Paola Gori-Giorgi, Andreas Gorling, Tim Gould, Stefan Grimme, Oleg Gritsenko, Hans Jorgen Aagaard Jensen, Erin R. Johnson, Robert O. Jones, Martin Kaupp, Andreas M. Koster, Leeor Kronik, Anna Krylov, Simen Kvaal, Andre Laestadius, Mel Levy, Mathieu Lewin, Shubin Liu, Pierre-Francois Loos, Neepa T. Maitra, Frank Neese, John P. Perdew, Katarzyna Pernal, Pascal Pernot, Piotr Piecuch, Elisa Rebolini, Lucia Reining, Pina Romaniello, Adrienn Ruzsinszky, Dennis R. Salahub, Matthias Scheffler, Peter Schwerdtfeger, Viktor N. Staroverov, Jianwei Sun, Erik Tellgren, David J. Tozer, Samuel B. Trickey, Carsten A. Ullrich, Alberto Vela, Giovanni Vignale, Tomasz A. Wesolowski, Xin Xu, Weitao Yang
Summary: This paper provides an informal review and discussion on the history, present status, and future of density-functional theory (DFT) by 70 workers in the field. The format of a roundtable discussion allowed participants to express their views through 302 individual contributions to a preset list of 26 questions. Supported by a bibliography of 777 entries, the paper offers a comprehensive snapshot of DFT in 2022.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Tim Gould, Stephen G. Dale
Summary: Large benchmark sets are useful for analyzing the performance of density functional theory, but they may miss cases where approaches fail badly. To address this issue, we introduce a series of 'poison' benchmark sets that represent the most difficult-to-model systems. These sets can help in developing new approximations, identifying weak points in existing ones, and selecting appropriate methods for computational studies involving difficult physics.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)