Size-Dependent Dielectric Properties of Liquid Water Clusters

2002 ◽  
pp. 284-298 ◽  
Author(s):  
Joel E. Boyd ◽  
Ari Briskman ◽  
Alan Mikhail ◽  
Vicki Colvin ◽  
Daniel Mittleman
Keyword(s):  
Dielectric Properties ◽  
Liquid Water ◽  
Water Clusters ◽  
Size Dependent

Reciprocal Polarizable Embedding with a Transferable H2O Potential Function II: Application to (H2O)n Clusters & Liquid Water

2019 ◽  
Author(s):  
Asmus Ougaard Dohn ◽  
Elvar Jónsson ◽  
Hannes Jonsson
Keyword(s):  
Density Functional Theory ◽  
Liquid Water ◽  
Density Functional ◽  
Water Clusters ◽  
Theory Model ◽  
Coupling Scheme ◽  
Functional Theory ◽  
Total Polarization ◽  
Electrostatic Embedding ◽  
Polarizable Embedding

The manuscript analyzes the accuracy of our recently developed reciprocal polarizable embedding scheme, where a density functional theory model of the QM region is coupled to a dipole- and quadrupole polarizable water potential of the MM region. We present calculations of water clusters and liquid water where we analyze the energy, atomic forces and total polarization to demonstrate that artifacts in energy and polarization introduced by the QM/MM coupling are small and well-behaved. Furthermore, our methodology improves the consistency of the structure of optimized water hexamer geometries when compared to results obtained with models that neglect polarization. Additionally, the manuscript provides evidence that our coupling scheme eliminates artifacts in the structure of liquid water obtained with simpler electrostatic embedding models.

ChemInform Abstract: Computational Studies of Atmospherically-Relevant Chemical Reactions in Water Clusters and on Liquid Water and Ice Surfaces

ChemInform ◽  
2015 ◽  
Vol 46 (17) ◽  
pp. no-no
Author(s):  
R. Benny Gerber ◽  
Mychel E. Varner ◽  
Audrey D. Hammerich ◽  
Sampsa Riikonen ◽  
Garold Murdachaew ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Liquid Water ◽  
Water Clusters ◽  
Computational Studies ◽  
Ice Surfaces ◽  
Atmospherically Relevant

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

scholarly journals Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

2020 ◽  
Author(s):  
Tianyu Zhu ◽  
Troy Van Voorhis
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid Water ◽  
Density Functional ◽  
Bulk Water ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Design Strategies ◽  
Total Electron Density ◽  
Total Electron

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

scholarly journals Understanding the Dipole Moment of Liquid Water from a Self-Attractive Hartree Decomposition

2020 ◽  
Author(s):  
Tianyu Zhu ◽  
Troy Van Voorhis
Keyword(s):  
Dipole Moment ◽  
Dielectric Properties ◽  
Liquid Water ◽  
Density Functional ◽  
Bulk Water ◽  
Dynamics Simulation ◽  
Ab Initio Molecular Dynamics ◽  
Design Strategies ◽  
Total Electron Density ◽  
Total Electron

<p>The dipole moment of a single water molecule in liquid water has been a critical concept for understanding water’s dielectric properties. In this work, we investigate the dipole moment of liquid water through a self-attractive Hartree (SAH) decomposition of total electron density computed by density functional theory, on water clusters sampled from ab initio molecular dynamics simulation of bulk water. By adjusting one parameter that controls the degree of density localization, we reveal two distinct pictures of water dipoles that are consistent with bulk dielectric properties: a localized picture with smaller and less polarizable monomer dipoles, and a delocalized picture with larger and more polarizable monomer dipoles. We further uncover that the collective dipole-dipole correlation is stronger in the localized picture and is key to connecting individual dipoles with bulk dielectric properties. Based on these findings, we suggest considering both individual and collective dipole behaviors when studying the dipole moment of liquid water, and propose new design strategies for developing water models.</p>

Size Dependent Dielectric Properties of TiO2 Nanoparticles

2020 ◽  
Vol 833 ◽  
pp. 147-151
Author(s):  
K.K. Anjali ◽  
A. Uma Maheswari ◽  
Manickam Sivakumar
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Surface Defects ◽  
Peak Shift ◽  
Chemical Precipitation ◽  
Space Charge Polarization ◽  
Precipitation Method ◽  
Bandgap Energy ◽  
Size Dependent ◽  
Mobility Of Charge Carriers

In this study, influence of nanoparticles size on optical and dielectric properties of TiO2 nanoparticles is investigated through thermal treatment of hydrous amorphous titania synthesized by chemical precipitation method at temperatures 300 °C and 600 °C. The average sizes of nanoparticles estimated respectively are ~ 8 nm and ~ 22 nm. Although the optical bandgap energy of both samples remains the same the Eg Raman mode observed at 144 cm-1 for bulk TiO2 is shifted to 150 cm-1 only for nanoparticles calcined at 300 °C. The shift is ascribed to the size as well as higher density of surface defects. Moreover, the presence of surface defects like oxygen vacancies which provide effective sites for catalytic reaction are confirmed by EPR and photoluminescence studies. The oxygen vacancies enhances space charge polarization and consequently results in higher dielectric constant. In addition, the peak shift of loss tangent which determines the mobility of charge carriers is found to be size dependent. Hence calcination temperature has significant influence on defect levels which in turn determine the optical and dielectric properties of TiO2 nanoparticles.

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