We describe a finite-field approach to compute density response functions, which allows for efficient G W and G WΓ calculations beyond the random phase approximation. The method is easily applicable to density functional calculations performed with hybrid functionals. We present results for the electronic properties of molecules and solids, and we discuss a general scheme to overcome slow convergence of quasiparticle energies obtained from G WΓ calculations, as a function of the basis set used to represent the dielectric matrix.
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http://dx.doi.org/10.1021/acs.jctc.8b00864 | DOI Listing |
Spectrochim Acta A Mol Biomol Spectrosc
November 2024
Department of Studies in Industrial Chemistry, Mangalore University, Mangalagangothri 574199, India.
In this article, the structural and nonlinear optical behaviour of a chalcone derivative, (2E)-1-(4-ethoxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one have been studied. FT-IR, FT-Raman, and NMR spectroscopy were analyzed to validate the molecular structure. To predict the nonlinear optical characteristics of the chalcone, the DFT approach was used and the experimental results were corroborated by the computations.
View Article and Find Full Text PDFPLoS One
March 2024
Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta, Canada.
In the Internet of Things (IoT), there are often devices that are computationally too constrained to establish a security key using traditional key distribution mechanisms such as those based on the Diffie-Hellman key exchange. To address this, current solution commonly rely on key predistribution schemes (KPSs). Among KPSs, the Blom scheme provably provides the highest resilience against node capture attacks.
View Article and Find Full Text PDFNature
October 2022
DeepMind, London, UK.
Improving the efficiency of algorithms for fundamental computations can have a widespread impact, as it can affect the overall speed of a large amount of computations. Matrix multiplication is one such primitive task, occurring in many systems-from neural networks to scientific computing routines. The automatic discovery of algorithms using machine learning offers the prospect of reaching beyond human intuition and outperforming the current best human-designed algorithms.
View Article and Find Full Text PDFRev Sci Instrum
September 2022
School of Control Science and Engineering, Tiangong University, Tianjin, China.
Electrical impedance tomography (EIT) technology is an important imaging approach to show the conductivity distribution of the area noninvasively. Recently, 3D EIT has been extensively studied for its more comprehensive display of electrical properties. Nonetheless, most 3D EIT electrode models are based on multilayer ring electrodes and only suitable for specific scenarios.
View Article and Find Full Text PDFJ Comput Chem
January 2023
Research Group of General Chemistry (ALGC), Vrije Universiteit Brussel, Brussels, Belgium.
The necessity of the recent incorporation of new external variables in the context of conceptual DFT (CDFT) is discussed based on the ever-increasing portfolio of experimental reaction conditions in the endeavor of experimentalists to synthesize new molecules with unprecedented properties. Electric and magnetic fields (ε and B), mechanical forces (F), and confinement are proposed as valuable new variables, extending conventional CDFT and its associated response functions. A finite field approach is used to calculate the evolution of both global and local descriptors in a selected series of atomic and molecular applications, and from it derive new response function involving, with one exception, the first derivative to the field considered.
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