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Showing 1 to 20 of 23 for “"Density functionals"”.
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Theory of density functionals
<p>Density functional theory is an alternative quantum mechanical theory that offers simple ways of performing calculations of the electronic properties of matter. Many different methods derive from density functional theory. The most appealing for its simplicity and rigor is the theory of Kohn and …
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Hybrid density functionals with proper exact exchange
Hybrid density functionals have the best overall performance among standard density func-tional approximations (DFA). According to their original design, hybrid DFAs are supposedto use the exact exchange (EXX). However, when hybrid functionals were originally intro-duced, there was no simple method …
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Correcting the Self-Interaction Error of Approximate Density Functionals
Common density functional approximations (DFAs) for the exchange-correlation energy suffer from self-interaction error (SIE), which is believed to be the cause of many of the failures of these approximations, such as poor description of charge transfer and transition states of chemical reactions. …
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Towards Systematic Improvement of Density Functional Approximations
<p>Density functional theory is a formally exact theory to describe ground state properties due to the existence of the exact functional. In practice, the usefulness of density functional theory relies on the accuracy of density functional approximations. After decades of effort of functional …
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Self-interaction and charge transfer in organic semiconductors
… considered as a convenient alternative. Hence, density functional theory (DFT) naturally arises as the method of choice. However, although in theory DFT yields an exact formulation of quantum mechanics, the quality of the results obtained from DFT calculations in practice strongly depends on the …
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First-principles transition-metal catalysis : efficient and accurate approaches for studying enzymatic systems
… respectively. We find that errors from common density functionals which are over 1.0 eV are greatly reduced to on average 0.1 eV when the DFT+U approach is implemented as compared against experiment and highly accurate but expensive quantum chemistry. We also improve structural and vibrational …
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MICROSCOPIC THEORY OF INFINITE NUCLEAR MATTER AND NON-EMPIRICAL ENERGY FUNCTIONALS
Nuclear density functional theory (DFT) and ab initio theory are complementary approaches to nuclear structure. DFT can be applied to the whole nuclear chart, but relies on empirical energy density functionals (EDFs). As a consequence, predictions in regions where experimental data are lacking, …
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Modeling non-radiative processes in solar materials
… to capture. Principally using time-dependent density functional theory, we are able to reproduce the experimental rates and, moreover, the fluorescence quantum yield, quite accurately. The next chapter then goes into extensions of the methodology discussed and analyzed in the prior chapter. …
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Construction of first-principles density functional approximations and their applications to materials
Kohn-Sham density functional theory is a rigorous formulation of many-electron quantum mechanics which, for practical purposes, requires approximation of one term in its total energy expression: the exchange-correlation energy. This work elucidates systematic methods for constructing approximations …
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Binary mixtures of rod-like colloids
… is derived on the basis of microscopic density functionals in the Parsons-Lee and Ramakrishnan-Youssuf approximations. The result is a mesoscopic free energy given in terms of a set of orientational order parameter tensors (one for each component of the mixture) and their gradients. In …
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Exploring Molecular Systems From Chemical Physics To Biochemistry Using Classical And Quantum Mechanics
… Chapter 3 is a survey of currently popular density functional methods and their ability to calculate accurate excitation energies and intensities of some organic molecules and simple first row transition metal complexes. Choice of a reasonable basis set seemed to have little effect on the …
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Density-functional Theory Applied To Problems In Catalysis And Electrochemistry
… surfaces below one monolayer coverage using density-functional theory. The results of this study provide a theoretical framework for interpreting recent experimental results on the redox properties of water at ceria (111) surfaces. In particular, we have computed the structure and energetics …
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Multiscale Modeling Of The Hierarchical Structure Of Cellulose Nanocrystals
… modeling techniques.</p> <p>First-principle density functional theory and molecular dynamic simulations were utilized at the atomistic level. Longstanding issues regarding the elastic and thermal expansion anisotropies for crystalline cellulose have been studied in terms of the single-crystal …
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Taming unstable inverse problems: Mathematical routes toward high-resolution medical imaging modalities
… from knowledge of internal measurements of power density type. This problem finds applications in the medical imaging modalities of Electrical Impedance Tomography and Optical Tomography, and the fact that one considers power densities is justified in practice by assuming a coupling of this …
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BAYESIAN INFERENCE ON NUCLEAR DATA AND NEUTRON STAR OBSERVATIONS FOR THE NUCLEAR EQUATION OF STATE
… extent, in the interior of nuclei, where the density is roughly constant and the interaction is dominated by the nuclear force, and in neutron stars, where the high densities in their interior exceed the nuclear ones. Finite nuclei deliver information only on symmetric or quasi-symmetric …
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Towards Combined Computational and Experimental Studies on Toxicity of Silver Nanoparticles
… occur experimentally and by using B3LYP the best density functional in predicting the HOMO, LUMO and ΔEgap of CP-PAHs with overall MAE of 014 eV. The best absorption spectra otef CP-PAHs were predicted using B3LYP for geometry optimizations followed by TD-CAMB3LYP with MAE of 29 nm. All …
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Density Functional Theory modeling of heterogeneous reactions of hydrocarbon intermediates on silicon carbide: surrogate kinetic model development for Chemical Vapor Infiltration
… of decomposition on the substrate using Density Functional Theory is the key point of current research. By focusing on the adsorption, reaction, and desorption mechanisms that control SiC development, our method incorporates quantum mechanical models. Using Transition State Theory, the …
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The performance of density functional theory with the correlation consistent basis sets.
Density functional theory has been used in combination with the correlation consistent and polarization consistent basis sets to investigate the structures and energetics for a series of first-row closed shell and several second-row molecules of potential importance in atmospheric chemistry. The …
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