نتایج جستجو برای: dft
تعداد نتایج: 19542 فیلتر نتایج به سال:
We review the role of self-consistency in density functional theory. We apply a recent analysis to both Kohn-Sham and orbital-free DFT, as well as to Partition-DFT, which generalizes all aspects of standard DFT. In each case, the analysis distinguishes between errors in approximate functionals versus errors in the self-consistent density. This yields insights into the origins of many errors in ...
This paper proposes an efficient frequency estimator based on Chinese Remainder Theorem for undersampled waveforms. Due to the emphasis on frequency offset recognition (i.e., frequency shift and compensation) of small-point DFT remainders, compared to estimators using large-point DFT remainders, it can achieve higher noise robustness in low signal-to-noise ratio (SNR) cases and higher accuracy ...
Frequency estimation of complex sinusoidal signal parameters for mixed Gaussian and impulse noise environment is considered. We assume that the sinusoid has constant amplitude. The first stage in the proposed algorithm is calculation of the L-DFT forms for various parameters. Then, an optimal value of the L-DFT parameter is estimated as a value minimizing the L-DFT energy. Position of the L-DFT...
BACKGROUND A balanced nutrition schedule provides the essential substances for proper oral health. OBJECTIVES The aim of this study was to investigate the association between dental caries and body mass index in 6-11 year-old children in Zahedan. MATERIALS AND METHODS In this cross-sectional study 1213 children (670 girls, 543 boys) were included. Body mass index (BMI) and clinical examinat...
We present a density functional theory (DFT) for steady-state nonequilibrium quantum systems such as molecular junctions under a finite bias. Based on the steady-state nonequilibrium statistics that maps nonequilibrium to an effective equilibrium, we show that ground-state DFT (GS-DFT) is not applicable in this case and two densities, the total electron density and the density of current-carryi...
Ab initio and density functional methods have been employed to study bridge bonding of aluminum compounds. Results for geometry optimizations and vibrational frequency calculations are found to be consistent with the recent literature. Heats of formation for the aluminum compounds dimethylaluminum hydride and trimethylaluminum are poorly described with density functional theory (DFT) methods in...
BACKGROUND/AIM In this study, we aimed to investigate the additive effect of mesenchymal stem cells (MSC) and defibrotide (DFT) in a rat model of femoral arterial thrombosis. METHODS Thirty Sprague Dawley rats were included. An arterial thrombosis model by ferric chloride (FeCl3) was developed in the left femoral artery. The rats were equally assigned to 5 groups: Group 1-Sham-operated (witho...
Hybrid molecular dynamics (MD) simulations, in which the forces acting on the atoms are calculated by grid-based density functional theory (DFT) for a solute molecule and by a polarizable molecular mechanics (PMM) force field for a large solvent environment composed of several 10(3)-10(5) molecules, pose a challenge. A corresponding computational approach should guarantee energy conservation, e...
Over the last couple of years, it has been shown that Time Dependent Density Functional Theory (TD-DFT) is able to predict accurately and efficiently the polarizability of molecules, when using appropriate exchange-correlation potentials and (large) basis sets. In a previous paper, we compared the accuracy of the predicted mean polarizabilities of 15 organic molecules with experiment, and with ...
We compare the performance of four recently developed DFT methods (MPW1B95, MPWB1K, PW6B95, and PWB6K) and two previous, generally successful DFT methods (B3LYP and B97-1) for the calculation of stacking interactions in six nucleic acid bases complexes and five amino acid pairs and for the calculation of hydrogen bonding interactions in two Watson-Crick type base pairs. We found that the four n...
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