Taking Advantage of a Systematic Energy Non-linearity Error in Density Functional Theory for the Calculation of Electronic Energy Levels

2021 ◽  
Author(s):  
Bun Chan ◽  
William Dawson ◽  
Takahito Nakajima ◽  
Kimihiko Hirao
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Levels ◽  
Electronic Energy ◽  
Functional Theory ◽  
Linearity Error ◽  
Electronic Energy Levels

Probing Absolute Electronic Energy Levels in Hg-Doped CdTe Semiconductor Nanocrystals by Electrochemistry and Density Functional Theory

ChemPhysChem ◽  
2015 ◽  
Vol 17 (2) ◽  
pp. 244-252 ◽  
Author(s):  
Pravin P. Ingole ◽  
Vladimir Lesnyak ◽  
Laxman Tatikondewar ◽  
Susanne Leubner ◽  
Nikolai Gaponik ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Energy Levels ◽  
Semiconductor Nanocrystals ◽  
Electronic Energy ◽  
Functional Theory ◽  
Electronic Energy Levels

Developing orbital-free quantum crystallography: the local potentials and associated partial charge densities

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Vladimir Tsirelson ◽  
Adam Stash
Keyword(s):  
Density Functional Theory ◽  
Electron Density ◽  
Density Functional ◽  
Electronic Energy ◽  
Physical Content ◽  
Functional Theory ◽  
Orbital Free ◽  
The One ◽  
Physical And Chemical ◽  
Quantum Crystallography

This work extends the orbital-free density functional theory to the field of quantum crystallography. The total electronic energy is decomposed into electrostatic, exchange, Weizsacker and Pauli components on the basis of physically grounded arguments. Then, the one-electron Euler equation is re-written through corresponding potentials, which have clear physical and chemical meaning. Partial electron densities related with these potentials by the Poisson equation are also defined. All these functions were analyzed from viewpoint of their physical content and limits of applicability. Then, they were expressed in terms of experimental electron density and its derivatives using the orbital-free density functional theory approximations, and applied to the study of chemical bonding in a heteromolecular crystal of ammonium hydrooxalate oxalic acid dihydrate. It is demonstrated that this approach allows the electron density to be decomposed into physically meaningful components associated with electrostatics, exchange, and spin-independent wave properties of electrons or with their combinations in a crystal. Therefore, the bonding information about a crystal that was previously unavailable for X-ray diffraction analysis can be now obtained.

scholarly journals Taguchi-Assisted Optimization Technique and Density Functional Theory for Green Synthesis of a Novel Cu-MOF Derived From Caffeic Acid and Its Anticancerious Activities

2021 ◽  
Vol 9 ◽  
Author(s):  
Malihe Zeraati ◽  
Ali Mohammadi ◽  
Somayeh Vafaei ◽  
Narendra Pal Singh Chauhan ◽  
Ghasem Sargazi
Keyword(s):  
Density Functional Theory ◽  
Caffeic Acid ◽  
Density Functional ◽  
Energy Levels ◽  
Optimization Technique ◽  
Nitrogen Adsorption ◽  
High Porosity ◽  
Anticancer Activities ◽  
Functional Theory ◽  
Sem Analyses

In this paper, we have reported an innovative greener method for developing copper-metal organic frameworks (Cu-MOFs) using caffeic acid (CA) as a linker extracted from Satureja hortensis using ultrasonic bath. The density functional theory is used to discuss the Cu-MOF-binding reaction mechanism. In order to achieve a discrepancy between the energy levels of the interactive precursor orbitals, the molecules have been optimized using the B3LYP/6–31G method. The Taguchi method was used to optimize the key parameters for the synthesis of Cu-MOF. FT-IR, XRD, nitrogen adsorption, and SEM analyses are used to characterize it. The adsorption/desorption and SEM analyses suggested that Cu-MOF has a larger surface area of 284.94 m2/g with high porosity. Cu-MOF has shown anticancer activities against the human breast cancer (MDA-MB-468) cell lines, and it could be a potent candidate for clinical applications.

BIS(BIPYRIDYL)-RU(II)-1-BENZOYL-3-(PYRIDINE-2-YL)-1H-PYRAZOLE AS POTENTIAL PHOTOSENSITISER: EXPERIMENTAL AND DENSITY FUNCTIONAL THEORY STUDY

2017 ◽  
Vol 79 (5-3) ◽  
Author(s):  
Wun-Fui Mark-Lee ◽  
Febdian Rusydi ◽  
Lorna Jeffery Minggu ◽  
Takashi Kubo ◽  
Mohammad Kassim
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Energy Levels ◽  
Spectroscopic Techniques ◽  
Functional Theory ◽  
Injection Process ◽  
Highest Occupied Molecular Orbital ◽  
Ligand Charge Transfer ◽  
Td Dft

Ru(II) complexes, [Ru(bpy)2(m-R-L)](PF6)2 where bpy = 2,2’-bipyridyl and  m-R-L= 1-(meta-R)-benzoyl-3-(pyridine-2-yl)-1H-pyrazole derivatives (R = H, CH3 and Cl) abbreviated as RuL, Ru(m-CH3-L) and Ru(m-Cl-L) complexes, respectively, were synthesized and characterized with spectroscopic techniques namely, infrared, UV-Vis and nuclear magnetic resonance (NMR), photoluminescence and mass spectroscopy. Density functional theory (DFT) and time-dependent (TD) DFT calculations were carried out to study the structural and electronic features of the molecules. These Ru(II) complexes exhibit photo-electronic properties required for a photosensitiser in a TiO2-catalysed photoelectrochemical (PEC) cell. In-depth understanding of the R-L fragment functionality is important to tune the photo-electronic properties of the Ru(II) complex. The highest-occupied molecular orbital (HOMO) is mainly localized at the Ru(II) centre, while the LUMO is dominantly spread across the R-L ligand. The Ru(II) complexes showed favourable metal-to-ligand charge transfer (MLCT) energy levels, which are comparably higher than the conduction band of TiO2 to facilitate electron injection process. Among the Ru(II) complexes, Ru(m-Cl-L) comparatively possesses the highest photoluminescence quantum yield and has the potential to be applied as photosensitiser in PEC systems.

STRUCTURES AND SPECTROSCOPIC PROPERTIES OF THREE AROMATIC HETEROCYCLIC DYE PHOTOSENSITIZERS

2013 ◽  
Vol 12 (06) ◽  
pp. 1350055
Author(s):  
YUANZUO LI ◽  
CHAOFAN SUN ◽  
LINPO YANG
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Electron Transition ◽  
Spectroscopic Properties ◽  
Molecular Orbitals ◽  
Functional Theory ◽  
Solvent Phase ◽  
Charge Difference Density

The ground-state structures and absorption spectra of three dyes, carbazole, phenothiazine and diphenylamine, were studied by the density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The strong absorption peak, electron transition as well as the energy levels of molecular orbitals were obtained and compared in the gas and solvent phase. Furthermore, we further calculated the effect of the expanding conjugated bridge on the absorption spectra and the energy levels of molecular orbitals. Visualized method of charge difference density (CDD) was used to show the direction of charge transfer in the molecules of interest during photo-excitation.

scholarly journals Density Functional Theory Study on the Electronic Structures of Oxadiazole Based Dyes as Photosensitizer for Dye Sensitized Solar Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Umer Mehmood ◽  
Ibnelwaleed A. Hussein ◽  
Khalil Harrabi ◽  
Shakeel Ahmed
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Electron Injection ◽  
Molecular Structures ◽  
Visible Absorption ◽  
Functional Theory ◽  
Oxidation Potentials

The molecular structures and UV-visible absorption spectra of complex photosensitizers comprising oxadiazole isomers as theπ-bridges were analyzed by density functional theory (DFT) and time-dependent DFT. The ground state and excited state oxidation potentials, HOMOs and LUMOs energy levels, and electron injection from the dyes to semiconductor TiO2have been computed in vacuum here. The results show that all of the dyes may potentially be good photosensitizers in DSSC. To justify the simulation basis, N3 dye was also simulated under the similar conditions. Simulated absorption spectrum, HOMO, LUMO, and band gap values of N3 were compared with the experimental values. We also computed the electronic structure properties and absorption spectra of dye/(TiO2)8systems to elucidate the electron injection efficiency at the interface. This work is expected to give proper orientation for experimental synthesis.

Density Functional Theory Study of TinO2n-m Clusters (n=1-4, m=0,1)

2012 ◽  
Vol 507 ◽  
pp. 79-82
Author(s):  
Dong Mei Li ◽  
Zhi Hua Xiong ◽  
Qi Xin Wan
Keyword(s):  
Density Functional Theory ◽  
Oxygen Atom ◽  
Density Functional ◽  
Energy Levels ◽  
Binding Energies ◽  
Terminal Oxygen Atom ◽  
Functional Theory ◽  
Energy Gaps ◽  
Equilibrium Geometries ◽  
Oxygen Atoms

Using density functional theory, the equilibrium geometries of TinO2n and TinO2n-1 clusters (n=1-4) have been obtained. It suggests that the structures of these two corresponding clusters are changed slightly, except for the number of terminal oxygen atoms. The electronic properties have also been investigated. The bond between Ti and terminal oxygen atom is found to be more covalent than other Ti-O bonds. It also indicates that by deleting one terminal oxygen atom, HOMO is mainly derived from titanium atoms with least coordination, but not from singly-coordination oxygen atoms as that in the stoichiometric clusters. Highest energy levels of least-coordination Ti atoms shift highly and they become more reactive. In addition, HOMO-LUMO energy gaps and binding energies were observed. The calculated results show that the energy gaps decrease quickly, except for Ti4O7 clusters and all the binding energies are relatively large.

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