scholarly journals Analysis of Resonant Soft X-ray Reflectivity of Anisotropic Layered Materials

Surfaces ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 18-30
Author(s):  
Luca Pasquali ◽  
Nicola Mahne ◽  
Angelo Giglia ◽  
Adriano Verna ◽  
Lorenzo Sponza ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Incidence Angle ◽  
Grazing Incidence ◽  
Quantitative Prediction ◽  
Matrix Formalism ◽  
Functional Theory ◽  
X Ray ◽  
Specular Reflectivity ◽  
Tetracarboxylic Dianhydride

We present here a method for the quantitative prediction of the spectroscopic specular reflectivity line-shape in anisotropic layered media. The method is based on a 4 × 4 matrix formalism and on the simulation from the first principles (through density functional theory—DFT) of the anisotropic absorption cross-section. The approach was used to simulate the reflectivity at the oxygen K-edge of a 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) thin film on Au(111). The effect of film thickness, orientation of the molecules, and grazing incidence angle were considered. The simulation results were compared to the experiment, permitting us to derive information on the film geometry, thickness, and morphology, as well as the electronic structure.

THE Ge(001) SURFACE RECONSTRUCTION: DFT AND MCS

1999 ◽  
Vol 06 (06) ◽  
pp. 1045-1051 ◽  
Author(s):  
YOSHIHIDE YOSHIMOTO ◽  
YOSHIMICHI NAKAMURA ◽  
HIROSHI KAWAI ◽  
MASARU TSUKADA ◽  
MASATOSHI NAKAYAMA
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Density Functional ◽  
First Principles Calculation ◽  
Transient Temperature ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Flip Flop ◽  
X Ray

The problem of relative energetic stabilities of the high order reconstructions of the Ge(001) surface is revisited by a more refined first-principles calculation based on density functional theory. Using this result, we performed a Monte Carlo simulation of the phase transition, and obtained 315 K as the transition temperature of p(2× 1) → c(4× 2). This reproduces fairly well the transient temperature (250–350 K) observed by an X-ray diffraction experiment. The obtained geometry of the c(4× 2) structure compares well with an X-ray diffraction experiment. The potential energy curves of flip-flop motions of both single dimer and dimer in type-P defect are also obtained.

scholarly journals Operando XANES from first-principles and its application to iridium oxide

2020 ◽  
Vol 22 (19) ◽  
pp. 10807-10818 ◽  
Author(s):  
Francesco Nattino ◽  
Nicola Marzari
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
First Principles ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Applied Potential ◽  
Functional Theory ◽  
X Ray ◽  
Continuum Description ◽  
X Ray Absorption

Density-functional theory calculations augmented with a continuum description of the electrochemical environment are implemented to simulated X-ray absorption spectra as a function of the applied potential.

scholarly journals Requirements of first-principles calculations of X-ray absorption spectra of liquid water

2016 ◽  
Vol 18 (1) ◽  
pp. 566-583 ◽  
Author(s):  
Thomas Fransson ◽  
Iurii Zhovtobriukh ◽  
Sonia Coriani ◽  
Kjartan T. Wikfeldt ◽  
Patrick Norman ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Liquid Water ◽  
First Principles ◽  
Density Functional ◽  
Time Dependent ◽  
First Principles Calculations ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Absorption ◽  
Dependent Density

Transition-potential and time-dependent density functional theory XAS calculations are presented for water and ice, showing excellent agreement between TDDFT results and experimental spectra.

scholarly journals Structure and stability of silicene on Ag(111) reconstructions from grazing incidence x-ray diffraction and density functional theory

2019 ◽  
Vol 99 (20) ◽  
Author(s):  
A. Curcella ◽  
R. Bernard ◽  
Y. Borensztein ◽  
A. Resta ◽  
M. Lazzeri ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Structure And Stability

Search For New Piezoelectrics

2008 ◽  
Vol 1110 ◽  
Author(s):  
Panchapakesan Ganesh ◽  
Ronald Cohen
Keyword(s):  
Density Functional Theory ◽  
Ground State ◽  
First Principles ◽  
Density Functional ◽  
Relaxor Ferroelectrics ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Chemical Pressure ◽  
X Ray ◽  
Born Effective Charge

AbstractRecent first principles simulations using density functional theory and novel low temperature x-ray diffraction experiments show the existence of a high pressure morphtotropic phase boundary (MPB) in pure PbTiO3. In this paper we apply chemical pressure by substituting smaller atoms in the ABO3 ‘A’ and ‘B’ sites. We find that the ground state of layered PbSnTiO3 (PSnT) is Pmm2, and for rocksalt SnGeTiO3 and PbGeTiO3 is R3m. The polarization of PbSnTiO3 is large (1.13,0,0)C/m2 and is due to the large Born effective charge of the small ‘Sn’ atom. We estimate the d33 for PSnT to be about 2400 pC/N, which is as large as that of currently used relaxor ferroelectrics.

scholarly journals Multication perovskite 2D/3D interfaces form via progressive dimensional reduction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrew H. Proppe ◽  
Andrew Johnston ◽  
Sam Teale ◽  
Arup Mahata ◽  
Rafael Quintero-Bermudez ◽  
...  
Keyword(s):  
Dimensional Reduction ◽  
Density Functional ◽  
Grazing Incidence ◽  
Photovoltaic Devices ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Scattering ◽  
Carrier Extraction ◽  
Perovskite Photovoltaic

AbstractMany of the best-performing perovskite photovoltaic devices make use of 2D/3D interfaces, which improve efficiency and stability – but it remains unclear how the conversion of 3D-to-2D perovskite occurs and how these interfaces are assembled. Here, we use in situ Grazing-Incidence Wide-Angle X-Ray Scattering to resolve 2D/3D interface formation during spin-coating. We observe progressive dimensional reduction from 3D to n = 3 → 2 → 1 when we expose (MAPbBr3)0.05(FAPbI3)0.95 perovskites to vinylbenzylammonium ligand cations. Density functional theory simulations suggest ligands incorporate sequentially into the 3D lattice, driven by phenyl ring stacking, progressively bisecting the 3D perovskite into lower-dimensional fragments to form stable interfaces. Slowing the 2D/3D transformation with higher concentrations of antisolvent yields thinner 2D layers formed conformally onto 3D grains, improving carrier extraction and device efficiency (20% 3D-only, 22% 2D/3D). Controlling this progressive dimensional reduction has potential to further improve the performance of 2D/3D perovskite photovoltaics.

scholarly journals Combined DFT and XPS Investigation of Cysteine Adsorption on the Pyrite (1 0 0) Surface

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 366 ◽  
Author(s):  
Xingfu Zheng ◽  
Xuan Pan ◽  
Zhenyuan Nie ◽  
Yi Yang ◽  
Lizhu Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Interaction Mechanism ◽  
Energy Calculation ◽  
Ionic Bond ◽  
Frontier Orbitals ◽  
Functional Theory ◽  
Xps Spectra ◽  
X Ray

The adsorption of cysteine on the pyrite (1 0 0) surface was evaluated by using first-principles-based density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) measurements. The frontier orbitals analyses indicate that the interaction of cysteine and pyrite mainly occurs between HOMO of cysteine and LUMO of pyrite. The adsorption energy calculation shows that the configuration of the -OH of -COOH adsorbed on the Fe site is the thermodynamically preferred adsorption configuration, and it is the strongest ionic bond according to the Mulliken bond populations. As for Fe site mode, the electrons are found transferred from cysteine to Fe of pyrite (1 0 0) surface, while there is little or no electron transfer for S site mode. Projected density of states (PDOS) is analyzed further in order to clarify the interaction mechanism between cysteine and the pyrite (1 0 0) surface. After that, the presence of cysteine adsorption on the pyrite (1 0 0) surface is indicated by the qualitative results of the XPS spectra. This study provides an alternative way to enhance the knowledge of microbe–mineral interactions and find a route to improve the rate of bioleaching.

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