Structure, stability, and vibrational properties of small silver cluster

1997 ◽  
Vol 40 (1-4) ◽  
pp. 479-482 ◽  
Author(s):  
R. Poteau ◽  
J.-L. Heully ◽  
F. Spiegelmann
Keyword(s):  
Silver Cluster ◽  
Structure Stability ◽  
Vibrational Properties

Structure, stability, and vibrational properties of polymerizedC60

1995 ◽  
Vol 52 (20) ◽  
pp. 14963-14970 ◽  
Author(s):  
Dirk Porezag ◽  
Mark R. Pederson ◽  
Th. Frauenheim ◽  
Th. Köhler
Keyword(s):  
Structure Stability ◽  
Vibrational Properties

scholarly journals Compression Behavior and Vibrational Properties of New Energetic Material LLM-105 Analyzed Using the Dispersion-Corrected Density Functional Theory

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6831
Author(s):  
Tianming Li ◽  
Junyu Fan ◽  
Zhuoran Wang ◽  
Hanhan Qi ◽  
Yan Su ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
High Pressure ◽  
Uniaxial Compression ◽  
Density Functional ◽  
Structural Parameters ◽  
Energetic Material ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Detailed Knowledge ◽  
Functional Theory

The 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) is a newly energetic material with an excellent performance and low sensitivity and has attracted considerable attention. On the basis of the dispersion-corrected density functional theory (DFT-D), the high-pressure responses of vibrational properties, in conjunction with structural properties, are used to understand its intermolecular interactions and anisotropic properties under hydrostatic and uniaxial compressions. At ambient and pressure conditions, the DFT-D scheme could reasonably describe the structural parameters of LLM-105. The hydrogen bond network, resembling a parallelogram shape, links two adjacent molecules and contributes to the structure stability under hydrostatic compression. The anisotropy of LLM-105 is pronounced, especially for Raman spectra under uniaxial compression. Specifically, the red-shifts of modes are obtained for [100] and [010] compressions, which are caused by the pressure-induced enhance of the strength of the hydrogen bonds. Importantly, coupling modes and discontinuous Raman shifts are observed along [010] and [001] compressions, which are related to the intramolecular vibrational redistribution and possible structural transformations under uniaxial compressions. Overall, the detailed knowledge of the high-pressure responses of LLM-105 is established from the atomistic level. Uniaxial compression responses provide useful insights for realistic shock conditions.

Theoretical Study of Stability, Structure, and Optical Spectra of Ultra-Small Silver Clusters Using Density Functional Theory

2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah
Keyword(s):  
Density Functional Theory ◽  
Formation Mechanism ◽  
Density Functional ◽  
Cluster Formation ◽  
Experimental System ◽  
Silver Cluster ◽  
Optical Spectra ◽  
Structure Stability ◽  
Silver Clusters ◽  
Functional Theory

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.

scholarly journals Direct Orange 26 Dye Environmental Degradation: Experimental Studies (UV, Mass and Thermal) in Comparison With Computational Exploration Hydrogen Bonding Analysis of TD-DFT Calculations

2021 ◽  
Author(s):  
Zahraa A. M. Abo-Ayad ◽  
Mohamed A. Zayed ◽  
Mahmoud A Noamaan
Keyword(s):  
Hydrogen Bonding ◽  
Dft Calculations ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Population Analysis ◽  
Experimental Studies ◽  
Calculated Data ◽  
Structure Stability ◽  
Vibrational Properties ◽  
Td Dft

Abstract The importance of this study stems from, it concentrates on new approach applying both practical and theoretical aspects to study structure stability of Direct orange dye 26 (DO26) as an important dye widely used for dyeing of cotton or viscose for red orange direct printing. The stable dyes are so difficult to remove, decolorized and/ or degrade, in pure solution or in wastewater samples, without using powerful removal environmental techniques electrochemical oxidations suggest and efficiently used in our Lab. Therefore, it is very important to compare between practical thermal and mass results as efficient techniques in studying dye stability, in comparison with theoretical results using Gaussian program for structural stability identification of DO26 dye, via careful inspection of various phenomena detected in its two symmetrical arms around urea center. Direct orange dye 26 (DO26) structure has been studied applying both practical spectroscopic and theoretical investigations. DFT-B3LYP/6-311++G(d,p) calculations and the electronic vibrational properties are performed to investigate its structure stability and consequently its degradation and removal from its environmental media. Correlation is found between experimental and calculated data. An intra-molecular hydrogen bonding interaction had been detected and characterized in dye skeleton. The hydrogen bonding present in the dye structure affecting its vibrational properties had been discussed. Natural population analysis like HOMO and LUMO and high quality molecular electrostatic potential plots along with various electronics had been presented at the same level of theory. Chemical reactivity descriptors from conceptual density functional theory point of view, structure activity relationship descriptor were obtained. The experimental UV/Visible, FT-IR, mass and GC-mass spectral data of the dye DO26 (D1) had been presented. These data had been supported by TD-DFT calculations to simulate the experimental spectra with computing the natural transition orbitals (NTO) and the orbital composition. The variation of charge transfer length (Δr) and variation in its dipole moment with respect to ground state (ΔmCT) had been computed in order to study the charge redistribution due to the excitations. Actually there is a problem that, degradation of this dye in wastewater by different techniques leads to various unknown fragments but on using theoretical possibilities it can be expected what happened in practical work.

Theoretical Study of Stability, Structure, and Optical Spectra of Ultra-Small Silver Clusters Using Density Functional Theory

2020 ◽  
Author(s):  
mohsen farshad ◽  
Duwage Perera ◽  
jayendran Rasaiah
Keyword(s):  
Density Functional Theory ◽  
Formation Mechanism ◽  
Density Functional ◽  
Cluster Formation ◽  
Experimental System ◽  
Silver Cluster ◽  
Optical Spectra ◽  
Structure Stability ◽  
Silver Clusters ◽  
Functional Theory

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.

Thermal and vibrational properties of silica xerogels

1998 ◽  
Vol 77 (2) ◽  
pp. 333-340 ◽  
Author(s):  
A. Fontana, F. Rossi, G. Carini, G. D'
Keyword(s):  
Vibrational Properties ◽  
Silica Xerogels

Development and Psychometric Evaluation of a Revised Sense of Coherence Scale

2018 ◽  
Vol 34 (3) ◽  
pp. 206-215 ◽  
Author(s):  
Rahel Bachem ◽  
Andreas Maercker
Keyword(s):  
Posttraumatic Growth ◽  
Factor Structure ◽  
Sense Of Coherence ◽  
Psychological Health ◽  
Psychometric Evaluation ◽  
Health Indicators ◽  
Structure Stability ◽  
Confirmatory Factor Analyses ◽  
Reliability Factor ◽  
Two Samples

Abstract. The present study introduces a revised Sense of Coherence (SOC) scale, a new conceptualization and operationalization of the resilience indicator SOC. It outlines the scale development and aims for testing its reliability, factor structure, and validity. Literature on Antonovsky’s SOC (SOC-A) was critically reviewed to identify needs for improving the scale. The scale was investigated in two samples. Sample 1 consisted of 334 bereaved participants, Sample 2 of 157 healthy controls. The revised SOC Scale, SOC-A, and theoretically relevant questionnaires were applied. Explorative and confirmatory factor analyses established a three-factor structure in both samples. The revised SOC Scale showed significant but discriminative associations with related constructs, including self-efficacy, posttraumatic growth, and neuroticism. The revised measure was significantly associated with psychological health indicators, including persistent grief, depression, and anxiety, but not to the extent as the previous SOC-A. Stability over time was sufficient. The study provides psychometric support for the revised SOC conceptualization and scale. It has several advantages over the previous SOC-A scale (unique variance, distinct factor structure, stability). The scale could be used for clinical and health psychological testing or research into the growing field of studies on resilience over the life span.

Diffusional and vibrational properties of water confined in very thin nanoporous glasses probed by light and neutron scattering

2000 ◽  
Vol 10 (PR7) ◽  
pp. Pr7-211-Pr7-214 ◽  
Author(s):  
V. Venuti ◽  
V. Crupi ◽  
S. Magazù ◽  
D. Majolino ◽  
P. Migliardo ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Vibrational Properties ◽  
Light And Neutron Scattering
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