scholarly journals DFT Studies on the Electronic Structures of 4-Methoxybenzonitrile Dye for Dye-Sensitized Solar Cell

2013 ◽  
Vol 12 ◽  
pp. 8-22 ◽  
Author(s):  
A. Prakasam ◽  
D. Sakthi ◽  
P.M. Anbarasan
Keyword(s):  
Electron Transfer ◽  
Electronic Structures ◽  
Density Functional ◽  
Hybrid Functional ◽  
Absorption Bands ◽  
Functional Theory ◽  
Dye Sensitizer ◽  
Injection Process ◽  
Electron Transfer Processes

The geometries, electronic structures, polarizabilities and hyperpolarizabilities of organic dye sensitizer 4-methoxybenzonitrile was studied based on Ab Initio HF and Density Functional Theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectrum was investigated by Time Dependent DFT (TDDFT). Features of the electronic absorption spectrum in the visible and near-UV regions were assigned based on TDDFT calculations. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in 4-methoxybenzonitrile is due to photoinduced electron transfer processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer 4-methoxybenzonitrile, is due to an electron injection process from excited dye to the semiconductor’s conduction band. The role of nitro group in 4-methoxybenzonitrile in geometries, electronic structures, and spectral properties were analyzed.

scholarly journals On topological materials as photocatalysts for water splitting by visible light

2021 ◽  
Author(s):  
Ahmad Ranjbar ◽  
Hossein Mirhosseini ◽  
Thomas D Küehne
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Water Oxidation ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Edge ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Hartree Fock ◽  
Topological Materials

Abstract We performed virtual materials screening to identify promising topological materials for photocatalytic water splitting under visible light irradiation. Topological compounds were screened based on band gap, band edge energy, and thermodynamics stability criteria. In addition, topological types for our final candidates were computed based on electronic structures calculated by means of hybrid density functional theory including exact Hartree-Fock exchange. Our final list contains materials which have band gaps between 1.0 eV and 2.7 eV in addition to band edge energies suitable for water oxidation and reduction. However, the topological types of these compounds calculated with the hybrid functional differ from those reported previously. To that end, we discuss the importance of computational methods for the calculation of atomic and electronic structures in materials screening processes.

scholarly journals Thermoelectric Properties of Sb-S System Compounds from DFT Calculations

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4707
Author(s):  
Hailong Yang ◽  
Pascal Boulet ◽  
Marie-Christine Record
Keyword(s):  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Dimensional Structure ◽  
Functional Theory ◽  
One Dimensional ◽  
Shed Light

By combining density functional theory, quantum theory of atoms in molecules and transport properties calculations, we evaluated the thermoelectric properties of Sb-S system compounds and shed light on their relationships with electronic structures. The results show that, for Sb2S3, the large density of states (DOS) variation induces a large Seebeck coefficient. Taking into account the long-range weak bonds distribution, Sb2S3 should exhibit low lattice thermal conductivity. Therefore, Sb2S3 is promising for thermoelectric applications. The insertion of Be atoms into the Sb2S3 interstitial sites demonstrates the electrical properties and Seebeck coefficient anisotropy and sheds light on the understanding of the role of quasi-one-dimensional structure in the electron transport. The large interstitial sites existing in SbS2 are at the origin of phonons anharmonicity which counteracts the thermal transport. The introduction of Zn and Ga atoms into these interstitial sites could result in an enhancement of all the thermoelectric properties.

scholarly journals Piezoresistivity of InAsP Nanowires: Role of Crystal Phases and Phosphorus Atoms in Strain-Induced Channel Conductances

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3249 ◽  
Author(s):  
In Kim ◽  
Han Seul Kim ◽  
Hoon Ryu
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Experimental Studies ◽  
Atomistic Simulations ◽  
Wurtzite Phase ◽  
Strong Electron ◽  
Functional Theory ◽  
Crystal Phases

Strong piezoresistivity of InAsP nanowires is rationalized with atomistic simulations coupled to Density Functional Theory. With a focal interest in the case of the As(75%)-P(25%) alloy, the role of crystal phases and phosphorus atoms in strain-driven carrier conductance is discussed with a direct comparison to nanowires of a single crystal phase and a binary (InAs) alloy. Our analysis of electronic structures presents solid evidences that the strong electron conductance and its sensitivity to external tensile stress are due to the phosphorous atoms in a Wurtzite phase, and the effect of a Zincblende phase is not remarkable. With several solid connections to recent experimental studies, this work can serve as a sound framework for understanding of the unique piezoresistive characteristics of InAsP nanowires.

scholarly journals Doping anatase TiO2 with group V-b and VI-b transition metal atoms: a hybrid functional first-principles study

2017 ◽  
Vol 19 (3) ◽  
pp. 1945-1952 ◽  
Author(s):  
Masahiko Matsubara ◽  
Rolando Saniz ◽  
Bart Partoens ◽  
Dirk Lamoen
Keyword(s):  
Transition Metal ◽  
First Principles ◽  
Density Functional ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Group V ◽  
Metal Atoms ◽  
Transition Metal Atoms ◽  
P Type

We investigate the role of transition metal atoms of group V-b (V, Nb, and Ta) and VI-b (Cr, Mo, and W) as n- or p-type dopants in anatase TiO2 using thermodynamic principles and density functional theory with the HSE06 hybrid functional.

COMPUTATIONAL STUDY OF BRIDGE-MEDIATED INTERVALENCE ELECTRON TRANSFER II: COUPLINGS IN DIFFERENT METALLOCENE COMPLEXES

2012 ◽  
Vol 11 (06) ◽  
pp. 1341-1356 ◽  
Author(s):  
YINXI YU ◽  
HAOBIN WANG ◽  
SHAOWEI CHEN
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Computational Study ◽  
Mixed Valence ◽  
Functional Theory ◽  
Transfer Processes ◽  
Mediated Electron Transfer ◽  
Bridge Structures ◽  
Electron Transfer Processes ◽  
The Relationship

The constrained density functional theory (CDFT) was used to study bridge-mediated electron transfer processes in mixed-valence systems with two identical metallocene (cobaltocene, ruthenocene, and nickelocene) moieties linked by various bridge structures. Based on the electronic coupling matrix elements obtained from the CDFT calculations, the relationship between the bridge linkage and the effectiveness of intervalence transfer was discussed.

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

2020 ◽  
Author(s):  
Tulin Okbinoglu ◽  
Pierre Kennepohl
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Td Dft ◽  
Nitrogen Bonds ◽  
X Ray Absorption ◽  
Related Compounds ◽  
And Chemical Properties

Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

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