Role of Chemistry and Crystal Structure on the Electronic Defect States in Cs-Based Halide Perovskites

The electronic structure of a series perovskites ABX3 (A = Cs; B = Ca, Sr, and Ba; X = F, Cl, Br, and I) in the presence and absence of antisite defect XB were systematically investigated based on density-functional-theory calculations. Both cubic and orthorhombic perovskites were considered. It was observed that for certain perovskite compositions and crystal structure, presence of antisite point defect leads to the formation of electronic defect state(s) within the band gap. We showed that both the type of electronic defect states and their individual energy level location within the bandgap can be predicted based on easily available intrinsic properties of the constituent elements, such as the bond-dissociation energy of the B–X and X–X bond, the X–X covalent bond length, and the atomic size of halide (X) as well as structural characteristic such as B–X–B bond angle. Overall, this work provides a science-based generic principle to design the electronic states within the band structure in Cs-based perovskites in presence of point defects such as antisite defect.

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Role of the Substituent Effect over the Squarate Oxocarbonic Ring: Spectroscopy, Crystal Structure, and Density Functional Theory Calculations of 1,2-Dianilinosquairane

The Journal of Physical Chemistry A ◽

10.1021/jp105346h ◽

2010 ◽

Vol 114 (37) ◽

pp. 10097-10109 ◽

Cited By ~ 28

Author(s):

Carlos E. Silva ◽

Hélio F. Dos Santos ◽

Nivaldo L. Speziali ◽

Renata Diniz ◽

Luiz Fernando C. de Oliveira

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Substituent Effect ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Functional Theory

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Electronic Origin of Defect States in Fe-Doped LiNbO3Ferroelectrics

Advances in Condensed Matter Physics ◽

10.1155/2016/2943173 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 9

Author(s):

Yuji Noguchi ◽

Ryotaro Inoue ◽

Masaru Miyayama

Keyword(s):

Density Functional ◽

Density Functional Theory Calculations ◽

Lattice Relaxation ◽

Light Illumination ◽

Defect State ◽

Defect States ◽

Functional Theory ◽

Orbital Hybridization ◽

Visible Light Illumination

We investigate the role of Fe in the electronic structure of ferroelectric LiNbO3by density-functional theory calculations. We show that Fe2+on the Li site (Fe2+Li) features a displacement opposite to the direction of spontaneous polarization and acts as a trigger for the bulk photovoltaic (PV) effect. In contrast to Fe3+on the Li site that forms the defect states (1e,a, and 2e) below the conduction band minimum, the reduction from Fe3+to Fe2+accompanied by a lattice relaxation markedly lowers only theastate (dz2) owing to a strong orbital hybridization with Nb-4d. Theastate ofFe2+Liprovides the highest electron-occupied defect state in the middle of the band gap. A reduction treatment of Fe-LN is expected to increase the concentration of Fe2+and therefore to enhance the PV effect under visible light illumination.

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The crystal structure of Na(NH4)Mo3O10·H2O

Powder Diffraction ◽

10.1017/s0885715617000380 ◽

2017 ◽

Vol 32 (2) ◽

pp. 140-147 ◽

Cited By ~ 2

Author(s):

Joel W. Reid ◽

James A. Kaduk ◽

Jeremy A. Olson

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Rietveld Refinement ◽

Software Package ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Parallel Tempering ◽

Powder Diffraction Data ◽

Functional Theory ◽

Synchrotron Powder Diffraction

The crystal structure of Na(NH4)Mo3O10·H2O has been solved by parallel tempering using the FOX software package with synchrotron powder diffraction data obtained from beamline 08B1-1 at the Canadian Light Source. Rietveld refinement, performed with the software package GSAS, yielded orthorhombic lattice parameters of a = 13.549 82(10), b = 7.618 50(6), and c = 9.302 74(7) Å (Z = 4, space group Pnma). The structure is composed of molybdate chains running parallel to the b-axis. The Rietveld refinement results were compared with density functional theory calculations performed with CRYSTAL14, and show excellent agreement with the calculated structure.

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DFT Studies of Graphene-Functionalised Derivatives of Capecitabine

Zeitschrift für Naturforschung A ◽

10.1515/zna-2017-0290 ◽

2017 ◽

Vol 72 (12) ◽

pp. 1131-1138 ◽

Cited By ~ 1

Author(s):

Mehdi Aramideh ◽

Mahmoud Mirzaei ◽

Ghadamali Khodarahmi ◽

Oğuz Gülseren

Keyword(s):

Density Functional ◽

Density Functional Theory Calculations ◽

Atomic Scale ◽

Phase System ◽

Molecular Models ◽

Functional Theory ◽

Atomic Properties ◽

Scale Properties ◽

Derivatives Of

AbstractCancer is one of the major problems for so many people around the world; therefore, dedicating efforts to explore efficient therapeutic methodologies is very important for researchers of life sciences. In this case, nanostructures are expected to be carriers of medicinal compounds for targeted drug design and delivery purposes. Within this work, the graphene (Gr)-functionalised derivatives of capecitabine (CAP), as a representative anticancer, have been studied based on density functional theory calculations. Two different sizes of Gr molecular models have been used for the functionalisation of CAP counterparts, CAP-Gr3 and CAP-Gr5, to explore the effects of Gr-functionalisation on the original properties of CAP. All singular and functionalised molecular models have been optimised and the molecular and atomic scale properties have been evaluated for the optimised structures. Higher formation favourability has been obtained for CAP-Gr5 in comparison with CAP-Gr3 and better structural stability has been obtained in the water-solvated system than the isolated gas-phase system for all models. The CAP-Gr5 model could play a better role of electron transferring in comparison with the CAP-Gr3 model. As a concluding remark, the molecular properties of CAP changed from singular to functionalised models whereas the atomic properties remained almost unchanged, which is expected for a carrier not to use significant perturbations to the original properties of the carried counterpart.

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Assessment of a variety of dispersion-corrected density functional theory calculations used in molecular crystal structure prediction

Journal of Cheminformatics ◽

10.1186/1758-2946-4-s1-o15 ◽

2012 ◽

Vol 4 (S1) ◽

Author(s):

Bernd Doser ◽

Marcus A Neumann

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Structure Prediction ◽

Molecular Crystal ◽

Density Functional ◽

Density Functional Theory Calculations ◽

Crystal Structure Prediction ◽

Functional Theory

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Synthesis, crystal structure, photophysical properties, density functional theory calculations and molecular docking studies on Cd(II) complex of 4,4′-dimethyl-2,2′-dipyridyl

Journal of Molecular Structure ◽

10.1016/j.molstruc.2019.127288 ◽

2020 ◽

Vol 1202 ◽

pp. 127288 ◽

Cited By ~ 2

Author(s):

Ömer Tamer ◽

Davut Avcı ◽

Necmi Dege ◽

Yusuf Atalay

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Molecular Docking ◽

Density Functional ◽

Photophysical Properties ◽

Density Functional Theory Calculations ◽

Docking Studies ◽

Functional Theory ◽

Molecular Docking Studies

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Oxides, Silicides, and Silicates of Zirconium and Hafnium; Density Functional Theory Study

MRS Proceedings ◽

10.1557/proc-716-b6.5 ◽

2002 ◽

Vol 716 ◽

Author(s):

Maciej Gutowski ◽

John E. Jaffe ◽

Chun-Li Liu ◽

Matt Stoker ◽

Anatoli Korkin

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Gate Dielectric ◽

Density Functional Theory Calculations ◽

Heat Of Formation ◽

Density Functional Theory Study ◽

Functional Theory ◽

Exchange Correlation ◽

The Difference ◽

Constituent Elements

AbstractIt is known that the chemistries of hafnium and zirconium are more nearly identical than for any other two congeneric elements. Thus, both zirconia and hafnia, with the dielectric constant K > 20, have emerged as potential replacements for silica (K = 3.9) as a gate dielectric. We report an important difference between the zirconia/Si and hafnia/Si interfaces based on density functional theory calculations with the Perdew-Wang 91 exchange-correlation functional on the oxides, silicides, and silicates of Zr and Hf. The zirconia/Si interface has been found to be unstable with respect to formation of silicides whereas the hafnia/Si interface is stable. The difference between the two interfaces results from the fact that HfO2 is more stable than ZrO2 (i.e. has a larger heat of formation from its constituent elements) by more than 53 kJ/mol. The hafnium silicides, on the other hand, are less stable than zirconium silicides by ca. 20 kJ/mol.

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The Role of SiH3 Diffusion in Determining the Surface Smoothness of Plasma-Deposited Amorphous Si Thin Films: An Atomic-Scale Analysis

MRS Proceedings ◽

10.1557/proc-862-a3.2 ◽

2005 ◽

Vol 862 ◽

Author(s):

Mayur S. Valipa ◽

Tamas Bakos ◽

Eray S. Aydil ◽

Dimitrios Maroudas

Keyword(s):

Thin Films ◽

Density Functional ◽

Activation Barrier ◽

Density Functional Theory Calculations ◽

Atomic Scale ◽

Functional Theory ◽

Weak Adsorption ◽

Dynamics Simulations ◽

Hydrogenated Amorphous

AbstractDevice-quality hydrogenated amorphous silicon (a-Si:H) thin films grown under conditions where the SiH3 radical is the dominant deposition precursor are remarkably smooth, as the SiH3 radical is very mobile and fills surface valleys during its diffusion on the a-Si:H surface. In this paper, we analyze atomic-scale mechanisms of SiH3 diffusion on a-Si:H surfaces based on molecular-dynamics simulations of SiH3 radical impingement on surfaces of a-Si:H films. The computed average activation barrier for radical diffusion on a-Si:H is 0.16 eV. This low barrier is due to the weak adsorption of the radical onto the a-Si:H surface and its migration predominantly through overcoordination defects; this is consistent with our density functional theory calculations on crystalline Si surfaces. The diffusing SiH3 radical incorporates preferentially into valleys on the a-Si:H surface when it transfers an H atom and forms a Si-Si backbond, even in the absence of dangling bonds.

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Synthesis, Characterization, and Crystal Structure Determination of a New Lithium Zinc Iodate Polymorph LiZn(IO3)3

Crystals ◽

10.3390/cryst9090464 ◽

2019 ◽

Vol 9 (9) ◽

pp. 464 ◽

Cited By ~ 5

Author(s):

Hebboul ◽

Galez ◽

Benbertal ◽

Beauquis ◽

Mugnier ◽

...

Keyword(s):

Crystal Structure ◽

Density Functional Theory ◽

Density Functional ◽

Second Harmonic ◽

Infrared Absorption Spectrum ◽

Density Functional Theory Calculations ◽

Functional Theory ◽

Space Group ◽

X Ray ◽

Cell Parameters

Synthesis and characterization of anhydrous LiZn(IO3)3 powders prepared from an aqueous solution are reported. Morphological and compositional analyses were carried out by using scanning electron microscopy and energy-dispersive X-ray measurements. The synthesized powders exhibited a needle-like morphology after annealing at 400 °C. A crystal structure for the synthesized compound was proposed from powder X-ray diffraction and density-functional theory calculations. Rietveld refinements led to a monoclinic structure, which can be described with space group P21, number 4, and unit-cell parameters a = 21.874(9) Å, b = 5.171(2) Å, c = 5.433(2) Å, and  = 120.93(4)°. Density-functional theory calculations supported the same crystal structure. Infrared spectra were also collected, and the vibrations associated with the different modes were discussed. The non-centrosymmetric space group determined for this new polymorph of LiZn(IO3)3, the characteristics of its infrared absorption spectrum, and the observed second-harmonic generation suggest it is a promising infrared non-linear optical material.

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