Role of oxygen vacancies in the surface evolution of H at CeO2(111): a charge modification effect

2015 ◽  
Vol 17 (5) ◽  
pp. 3544-3549 ◽  
Author(s):  
Xin-Ping Wu ◽  
Xue-Qing Gong ◽  
Guanzhong Lu
Keyword(s):  
Density Functional ◽  
Diffusion Processes ◽  
Density Functional Theory Calculations ◽  
Coulomb Interactions ◽  
Processes And Reactions ◽  
Functional Theory ◽  
Surface Evolution ◽  
P Diffusion ◽  
A Charge

Diffusion processes and reactions of H at stoichiometric and reduced CeO2(111) surfaces have been studied by using density functional theory calculations corrected by on-site Coulomb interactions (DFT + U).

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

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1032
Author(s):  
Anirban Naskar ◽  
Rabi Khanal ◽  
Samrat Choudhury
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Covalent Bond ◽  
Density Functional Theory Calculations ◽  
Antisite Defect ◽  
Defect States ◽  
Functional Theory ◽  
Electronic Defect ◽  
Constituent Elements

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.

scholarly journals DFT Studies of Graphene-Functionalised Derivatives of Capecitabine

2017 ◽  
Vol 72 (12) ◽  
pp. 1131-1138 ◽  
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.

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

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.

scholarly journals Higher superconducting transition temperature by breaking the universal pressure relation

2019 ◽  
Vol 116 (6) ◽  
pp. 2004-2008 ◽  
Author(s):  
Liangzi Deng ◽  
Yongping Zheng ◽  
Zheng Wu ◽  
Shuyuan Huyan ◽  
Hung-Cheng Wu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Temperature ◽  
Transition Temperature ◽  
Density Functional ◽  
High Temperature Superconductors ◽  
Density Functional Theory Calculations ◽  
Universal Relation ◽  
Superconducting Transition ◽  
Functional Theory ◽  
A Charge

By investigating the bulk superconducting state via dc magnetization measurements, we have discovered a common resurgence of the superconducting transition temperatures (Tcs) of the monolayer Bi2Sr2CuO6+δ(Bi2201) and bilayer Bi2Sr2CaCu2O8+δ(Bi2212) to beyond the maximum Tcs (Tc-maxs) predicted by the universal relation between Tcand doping (p) or pressure (P) at higher pressures. The Tcof underdoped Bi2201 initially increases from 9.6 K at ambient to a peak at 23 K at 26 GPa and then drops as expected from the universal Tc-P relation. However, at pressures above 40 GPa, Tcrises rapidly without any sign of saturation up to 30 K at 51 GPa. Similarly, the Tcfor the slightly overdoped Bi2212 increases after passing a broad valley between 20 and 36 GPa and reaches 90 K without any sign of saturation at 56 GPa. We have, therefore, attributed this Tcresurgence to a possible pressure-induced electronic transition in the cuprate compounds due to a charge transfer between the Cu 3dx2−y2and the O 2pbands projected from a hybrid bonding state, leading to an increase of the density of states at the Fermi level, in agreement with our density functional theory calculations. Similar Tc-P behavior has also been reported in the trilayer Br2Sr2Ca2Cu3O10+δ(Bi2223). These observations suggest that higher Tcs than those previously reported for the layered cuprate high-temperature superconductors can be achieved by breaking away from the universal Tc-P relation through the application of higher pressures.

Theoretical Insights into the Role of Water Molecule in The Aqueous/Cu(111) Interface during Corrosion Pathway

2014 ◽  
Vol 19 (4) ◽  
pp. 235-240
Author(s):  
Jun Hu ◽  
Xiao-yong Fan ◽  
Chao-Ming Wang
Keyword(s):  
Water Molecule ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Adsorbed Water ◽  
Dipole Interaction ◽  
Hydrogen Atoms ◽  
Functional Theory ◽  
Adsorbed Water Molecule ◽  
The One

The absorption and possible reaction paths during corrosion have been systematically identified at the molecular level by us-ing density functional theory calculations. The results show that the co-adsorbed water molecule has a two-fold impact on the corrosive kinetics process. The one is the solvation effect, where water molecule affects the various reactions through ion dipole interaction, without bond fracture and formation. Another is the H-transfer mediator, where the bond of co-adsorbed water molecule breaks and regenerates in order to transfer hydrogen atoms.

The role of exchange–correlation functional on the description of multiferroic properties using density functional theory: the ATiO3 (A = Mn, Fe, Ni) case study

RSC Advances ◽  
2016 ◽  
Vol 6 (103) ◽  
pp. 101216-101225 ◽  
Author(s):  
Renan Augusto Pontes Ribeiro ◽  
Sergio Ricardo de Lazaro ◽  
Carlo Gatti
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Multiferroic Properties ◽  
Exchange Correlation

In this study, ab initio density functional theory calculations were performed on ATiO3 (A = Mn, Fe, Ni) materials for multiferroic applications.

scholarly journals Электронная структура и квадрупольные взаимодействия в перспективных катодных материалах Na-=SUB=-x-=/SUB=-M-=SUB=-y-=/SUB=-(MoO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-, M=Mn, Fe, Co и Ni

2019 ◽  
Vol 61 (5) ◽  
pp. 828
Author(s):  
Н.И. Медведева ◽  
А.В. Сердцев
Keyword(s):  
Density Functional ◽  
Resonance Method ◽  
Nuclear Magnetic Resonance Method ◽  
Coulomb Interactions ◽  
Functional Theory ◽  
Magnetic Resonance Method ◽  
The Density Functional Theory ◽  
Sodium Batteries ◽  
First Time

AbstractThe electronic structure and the magnetic properties of molybdates Na_ x M_ y (MoO_4)_3 (M = Mn, Fe, Co, and Ni) which are promising materials for sodium batteries have been studied in the framework of the density functional theory with the GGA and GGA+ U approximations for the first time. The calculations show that all the compounds are insulators. An important role of the correlation effects, provided by the on-site Coulomb interactions, was established in the formation of the band gap in these compounds. The quadrupole constants of  ^23Na nuclei are calculated in the nonmagnetic and ferromagnetic states within the GGA and GGA+ U approaches. It is shown that the quadrupole frequencies for nonequivalent crystallographic positions of sodium are in different frequency ranges, which allows to study the diffusion of sodium in these compounds by the Nuclear Magnetic Resonance method.

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