scholarly journals Theoretical Studies on the Structural, Electronic and Optical Properties of the New π-conjugated Copolymers Based on Carbazole and Thiophene

2011 ◽  
Vol 4 (1) ◽  
pp. 119 ◽  
Author(s):  
Z. El Maliki ◽  
M. Bouachrine ◽  
M. Hamidi ◽  
L. Bejjit ◽  
M. Haddad
Keyword(s):  
Optical Properties ◽  
Molecular Geometry ◽  
Dft Method ◽  
Optoelectronic Properties ◽  
Polymer Materials ◽  
Organic Polymer ◽  
Excitation Energies ◽  
Electronic And Optical Properties ◽  
Td Dft ◽  
Homo Lumo

This work reports a theoretical investigation of π-conjugated oligomers constituted by n units (n = 1-4) based on carbazole and ethylenedioxythiophene. The molecular geometry, torsional potential, electronic and optical properties of the oligomers [Cbz-(Edot)n-Cbz] (n = 1-4) are investigated using DFT (B3LYP/3-21G*) calculations. The discussion is focused on the influence of chain length on the properties of these copolymers. The analyses of torsional angles for [Cbz-(Edot)4-Cbz] reveal that the structure has a anti-planar conformation. The electronic properties of the molecules, HOMO, LUMO and Eg (HOMO-LUMO), are studied using B3LYP functional. The results have been compared with those of thiophene and ethylenedioxythiophene. The lowest excitation energies (Eex) and the maximal absorption wavelength (λabs) are studied using the TD/DFT, ZINDO and CIS methods. The electronic transitions of the absorption spectrum derived by TD/DFT method give useful structural and electronic information for designing novel conducting organic polymer materials. The bridging effect by C=C(CN)2 on the optoelectronic properties of the (carbazole-thiophene-carbazole) comonomer is investigated. Keywords: Conducting polymer; Carbazole-(Ethylenedioxythiophene)n-Carbazole comonomers; DFT Optoelectronic properties; absorption coefficient; Bridging effect. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i1.7450J. Sci. Res. 4 (1), 119-133 (2012)  

scholarly journals A DFT study of the effects of Sc doping on electronic and optical properties of CdS nanoparticles

2015 ◽  
Vol 33 (4) ◽  
pp. 782-791
Author(s):  
Shafiq Ur Rehman ◽  
Abdul Majid ◽  
Najmal Hassan ◽  
Abdul Shakoor ◽  
G. Murtaza ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Geometry Optimization ◽  
Blue Shift ◽  
Dft Method ◽  
Integration Scheme ◽  
Cds Nanoparticles ◽  
Electronic And Optical Properties ◽  
Numerical Integration Scheme ◽  
Homo Lumo

AbstractIn the present work a systematic study was carried out to understand the influence of Sc doping on electronic and optical properties of CdS nanoparticles. The geometry optimization and symmetry computation for CdS and Sc doped CdS nanoparticles using Density Functional Theory (DFT) on B3LYP level with the QZ4P for Cd and DZ2P for sulphur and Sc were performed by Amsterdam Density Functional (ADF). The results show that HOMO-LUMO gap as well as electronic and optical properties of CdS clusters vary with Sc doping. The HOMO-LUMO gap is affected by the dopant and its value decreases to 0.6 eV. Through considering the numerical integration scheme in the ADF package, we investigated different vibrational modes and our calculated Raman and IR spectra are consistent with the reported result. The calculated IR and Raman peaks of CdS and Sc doped CdS clusters were in the range of 100 to 289 cm−1, 60 cm−1 to 350 cm−1 and 99 cm−1 to 282 cm−1, 60 cm−1 to 350 cm−1, respectively, which was also confirmed by experiment as well as a blue shift occurrence. Subsequently, for deeper research of pure and doped CdS clusters, their absorption spectra were calculated using time-dependent DFT method.

STRUCTURAL, ELECTRONIC, AND OPTICAL PROPERTIES OF ZnxSy (x + y = 2 TO 4) NANOCLUSTERS: A B3LYP-DFT STUDY

2011 ◽  
Vol 10 (01n02) ◽  
pp. 341-344
Author(s):  
P. S. YADAV ◽  
D. K. PANDEY ◽  
S. AGRAWAL ◽  
B. K. AGRAWAL
Keyword(s):  
Optical Properties ◽  
Visible Region ◽  
Zero Point ◽  
Binding Energies ◽  
Ultraviolet Region ◽  
Point Energy ◽  
Electronic And Optical Properties ◽  
The Stability ◽  
The One ◽  
Homo Lumo

The stability, structural, electronic, and optical properties have been studied for most stable zinc sulfide nanoclusters Zn x S y (x + y = n = 2 to 4). A B3LYP-DFT/6-311G(3df) method is employed to optimize the geometries, and a TDDFT method is used for the study of the optical properties. The binding energies (BE), HOMO–LUMO gaps and the bond lengths have been obtained for all the clusters. We have considered also the zero point energy (ZPE) corrections ignored by the earlier workers. For a fixed value of n, we designate the most stable structure the one, which has maximum final binding energy per atom. The adiabatic and vertical ionization potentials (IP) and electron affinities (EA), charge on atoms, dipole moment, and optical properties have been investigated for the most stable structures. The nanoclusters containing large number of S atoms for each "n" are found to be most stable. Except for ZnS nanocluster, the HOMO–LUMO gap increases with the number of S atoms. Similarly, except for ZnS , IP and EA fluctuate with the cluster size but reveal downward trend. The optical absorption is quite weak in visible region but is strong in the ultraviolet region in most of the nanoclusters except a few. The growth of most stable nanoclusters may be possible in the experiments.

scholarly journals Structural, electronic and optical properties of 2,5-dichloro-p-xylene: experimental and theoretical calculations using DFT method

RSC Advances ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 1401-1412 ◽  
Author(s):  
G. Venkatesh ◽  
M. Govindaraju ◽  
C. Kamal ◽  
P. Vennila ◽  
S. Kaya
Keyword(s):  
Optical Properties ◽  
Vibrational Spectra ◽  
Theoretical Calculations ◽  
Dft Method ◽  
Electronic And Optical Properties ◽  
Ft Ir ◽  
Ft Raman

The vibrational spectra including FT-IR and FT-Raman for 2,5-dichloro-p-xylene (DCPX) have been recorded.

Electronic, optical and photocatalytic properties of three-layer perovskite Dion–Jacobson phase CsBa2M3O10(M = Ta, Nb): a DFT study

RSC Advances ◽  
2015 ◽  
Vol 5 (108) ◽  
pp. 88725-88735 ◽  
Author(s):  
Ehsan Zahedi ◽  
Mirabbos Hojamberdiev ◽  
Maged F. Bekheet
Keyword(s):  
Optical Properties ◽  
Uv Light ◽  
Dft Method ◽  
Dft Study ◽  
Photocatalytic Properties ◽  
Electronic And Optical Properties

This work discloses structural, electronic and optical properties of three-layer perovskite Dion–Jacobson phase CsBa2M3O10(M = Ta, Nb) using the DFT method. These semiconductors are UV-light-responsive photocatalysts.

scholarly journals ABSORPTION OF SOME SMALL SILVER CLUSTERS: DFT AND CASPT2 CALCULATIONS

2018 ◽  
Vol 55 (6A) ◽  
pp. 72
Author(s):  
Ngo Tuan Cuong
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Noble Gas ◽  
Silver Cluster ◽  
Dft Method ◽  
Basis Sets ◽  
Silver Clusters ◽  
Excitation Energies ◽  
Complete Active Space ◽  
Td Dft

Two quantum chemical methods which are the time-dependent density functional theory (TD-DFT) and the complete active space CASPT2/CASSCF have been used in modeling absorption spectra of silver clusters Agn (n = 2, 3, 4, 6, 8). There is an overall good agreement between TD-DFT and CASPT2 results for transition energies. The absorption spectra of the Agn clusters examined can reasonably be simulated using the excitation energies obtained by either TD-DFT or CASPT2 method.  The main result emerged from this calculation is that the TD-DFT method is suitable for treatment of excited states of Ag clusters. The choice of specific functionals and basis sets to be used in some cases induces important effects on the calculated spectra. It is also noteworthy to mention that for some clusters, the neutral Ag6 for instance, the effect of noble gas environment is significant, while for some others such as the neutral Ag8, it is not. Therefore, carrying out TD-DFT calculations to reproduce and to assign a given structure to an experimental absorption spectrum of a silver cluster, it is not only to select suitable functionals but also to take enough effects of environments into account. 

Novel Janus diamane C4FCl: a stable and moderate bandgap semiconductor with huge excitonic effect

2021 ◽  
Author(s):  
Huabing Shu
Keyword(s):  
Optical Properties ◽  
First Principles ◽  
Optoelectronic Properties ◽  
The Novel ◽  
Two Dimensional ◽  
First Principles Calculations ◽  
Electronic And Optical Properties ◽  
The Stability ◽  
Excitonic Effect

Semiconducting two-dimensional Janus materials have drawn increasing attention for the novel optoelectronic properties. Here, employing first-principles calculations, we systematically explore the stability, electronic and optical properties of Janus diamane C4FCl....

Structural, electronic and optical properties of LiNbO3 using GGA-PBE and TB-mBJ functionals: A DFT study

2018 ◽  
Vol 32 (14) ◽  
pp. 1850168 ◽  
Author(s):  
M. Arshad Javid ◽  
Zafar Ullah Khan ◽  
Zahid Mehmood ◽  
Azeem Nabi ◽  
Fayyaz Hussain ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Lithium Niobate ◽  
Dielectric Function ◽  
Lithium Niobate Crystal ◽  
Structural Parameters ◽  
Dft Method ◽  
Bandgap Energy ◽  
Electronic And Optical Properties ◽  
Experimental Values

In the present work, first-principles calculations were performed to obtain the structural, electronic and optical properties of lithium niobate crystal using two exchange-correlation functionals (GGA-PBE and TB-mBJ). The calculated structural parameters were very close to the experimental values. TB-mBJ functional was found to be good when compared to LDA and GGA functionals in case of bandgap energy of 3.715 eV of lithium niobate. It was observed that the upper valence and lower conduction bands consist mainly the O-2p and Nb-4[Formula: see text] states, respectively. Furthermore, calculations for real and imaginary parts of frequency-dependent dielectric function [Formula: see text] of lithium niobate crystal were performed using TD-DFT method. The ordinary refractive index n[Formula: see text], extraordinary refractive index n[Formula: see text], its birefringence and absorption peaks in imaginary dielectric function [Formula: see text] were also calculated.

scholarly journals First-Principles Studies on Structural, Electronic and Optical Properties of Fe-doped Nis2 Counter Electrode for Dye-Sensitized Solar Cells using Dft+U

2020 ◽  
Vol 17 (2) ◽  
pp. 81
Author(s):  
Nur Aisyah Ab Malik Marwan ◽  
Nurakma Natasya Md Jahangir Alam ◽  
Mohd Hazrie Samat ◽  
Muhammad Zamir Mohyedin ◽  
Nur Hafiz Hussin ◽  
...  
Keyword(s):  
Optical Properties ◽  
Solar Cells ◽  
First Principles ◽  
Density Functional ◽  
Counter Electrode ◽  
Dye Sensitized Solar Cells ◽  
Dft Method ◽  
Electronic And Optical Properties ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

The structural, electronic and optical properties of nickel disulfide (NiS2) and iron (Fe)-doped NiS2 were computed by using first-principles calculations through the density functional theory (DFT) method. The Fe was used as a dopant element to understand the behavior and the key mechanism of Fe-doped NiS2 as a counter electrode in dye-sensitized solar cells (DSSC). The results indicated that the structural properties of the NiS2 as the cubic crystal structure with the space group Pa3 (205) (pyrite structure type) agree with experimental data. The density of states (DOS) of NiS2 and Fe-doped NiS2 shows a gapless bandgap due to Mott insulator behavior. As for optical properties, the optical absorption of NiS2 is shifted towards the infrared (IR) region when doping with Fe while the conductivity of Fe-doped NiS2 is slightly higher in conductivity. These optical properties show that Fe-doped NiS2 is good for photocatalytic activity and may provide an excellent electron charge transfer for a counter electrode in DSSC

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