Theoretical Study of the Stability, Structure, and Optical Spectra of Small Silver Clusters and Their Formation Using Density Functional Theory

Author(s):  
Mohsen Farshad ◽  
Duwage Charitha Perera ◽  
Jayendran C Rasaiah

An understanding of the mechanism of formation of small clusters would help to identify efficient routes to their synthesis. Here, we apply density functional theory (DFT) to study the free...

2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah

Our article is a systematic study toward understanding the mechanism of silver cluster formation. We calculated optical spectra of ultra-small silver clusters using time-dependent density functional theory (TDDFT) and compared our results with time-resolved UV-Vis spectra obtained from pulse radiolysis experiments during early stages of cluster formation. This comparative study indicates that the formation mechanism of silver clusters occurs through both monomer and ion addition growth pathways. Also, we calculated free energy of formation of small cationic and neutral clusters using density functional theory (DFT) which shows the thermodynamic stability of cationic clusters. In a conventional experimental system with the common reducing agents, the formation of cationic clusters is kinetically favored owing to the dominance of charged ions relative to neutral atoms in the system. While we show the stability of small cationic clusters relative to neutral clusters, collectively, we deduce that the monomer addition along with ion addition growth pathway is involved in silver cluster formation mechanism. We further show the effect of solvent and water ligands on structure, stability, and optical properties of small clusters.


2011 ◽  
Vol 217-218 ◽  
pp. 924-929
Author(s):  
Jin Hong Xue ◽  
Jing Chao Chen ◽  
Jie Yu ◽  
Jing Feng ◽  
Yong Pan ◽  
...  

Ca3Ru2O7 is new tpye of thermoelectric materials.A theoretical study is presented for the stability, electronic and magnetic properties of three phases of this new thermoelectric materials in the framework of density functional theory (DFT). The calculated cohesive energy is -7.94eV/unit. AFM2 are less stable than other pahses. Electronic calculations indicate that Ca3Ru2O7 is metallic in nature. The covalent bonds in these structures are due to orbital overlap between p bands of O and d bands of Ru, and DOS at Fermi level are dominated by d bands of Ru. FM phase have obvious magnetic moments.


2011 ◽  
Vol 347-353 ◽  
pp. 3489-3492
Author(s):  
Li Bin Shi ◽  
Hong Kuan Yuan

Using the first principle method based on density functional theory (DFT), we have studied the stability, structure, and electronic properties in (2 2), (3, 3), (4 4), (5 5), (6 6) armchair and (4 0), (5 0), (6 0) zigzag GaN nanotubes (GaN-NTs). In addition, the radius of N, Ga atoms, buckling separations, band gap and binding energy of (3 3) and (4 0) GaN-NTs in c-axis strain are investigated. We also explore the modification of density of states due to the strain along c-axis orientation. It is found that the strain can change conductive properties of (3 3) and (4 0) GaN-NTs.


2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah

Our article is a systematic study toward understanding the mechanism of silver cluster formation. We calculated optical spectra of ultra-small silver clusters using time-dependent density functional theory (TDDFT) and compared our results with time-resolved UV-Vis spectra obtained from pulse radiolysis experiments during early stages of cluster formation. This comparative study indicates that the formation mechanism of silver clusters occurs through both monomer and ion addition growth pathways. Also, we calculated free energy of formation of small cationic and neutral clusters using density functional theory (DFT) which shows the thermodynamic stability of cationic clusters. In a conventional experimental system with the common reducing agents, the formation of cationic clusters is kinetically favored owing to the dominance of charged ions relative to neutral atoms in the system. While we show the stability of small cationic clusters relative to neutral clusters, collectively, we deduce that the monomer addition along with ion addition growth pathway is involved in silver cluster formation mechanism. We further show the effect of solvent and water ligands on structure, stability, and optical properties of small clusters.


RSC Advances ◽  
2021 ◽  
Vol 11 (38) ◽  
pp. 23477-23490
Author(s):  
Yonggang Wu ◽  
Jihua Zhang ◽  
Bingwei Long ◽  
Hong Zhang

The ZnWO4 (010) surface termination stability is studied using a density functional theory-based thermodynamic approach. The stability phase diagram shows that O-Zn, DL-W, and DL-Zn terminations of ZnWO4 (010) can be stabilized.


2021 ◽  
Vol 37 (4) ◽  
pp. 805-812
Author(s):  
Ahissandonatien Ehouman ◽  
Adjoumanirodrigue Kouakou ◽  
Fatogoma Diarrassouba ◽  
Hakim Abdel Aziz Ouattara ◽  
Paulin Marius Niamien

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.


2021 ◽  
Vol 23 (37) ◽  
pp. 21078-21086
Author(s):  
Tomomi Shimazaki ◽  
Masanori Tachikawa

In this work, the excitation energies of asymmetric thiazolothizaole (TTz) dye molecules have been theoretically studied using dielectric-dependent density functional theory (DFT).


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