Second inflection point of water surface tension in the deeply supercooled regime revealed by entropy anomaly and surface structure using molecular dynamics simulations

2019 ◽  
Vol 21 (6) ◽  
pp. 3360-3369 ◽  
Author(s):  
Xiaoxiang Wang ◽  
Kurt Binder ◽  
Chuchu Chen ◽  
Thomas Koop ◽  
Ulrich Pöschl ◽  
...  
Keyword(s):  
Physical Chemistry ◽  
Molecular Dynamics ◽  
Surface Tension ◽  
Molecular Dynamics Simulations ◽  
Surface Structure ◽  
Water Surface ◽  
Inflection Point ◽  
Supercooled Water ◽  
Atmospheric Sciences ◽  
Dynamics Simulations

The surface tension of supercooled water is of fundamental importance in physical chemistry and materials and atmospheric sciences.

scholarly journals Interface Characteristics of Neat Melts and Binary Mixtures of Polyethylenes from Atomistic Molecular Dynamics Simulations

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1059
Author(s):  
Sanghun Lee ◽  
Curtis W. Frank ◽  
Do Y. Yoon
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Molecular Dynamics Simulations ◽  
Binary Mixtures ◽  
Surface Segregation ◽  
Surface Region ◽  
Polymer Chains ◽  
Methyl Groups ◽  
Free Standing ◽  
Dynamics Simulations

Molecular dynamics simulations of free-standing thin films of neat melts of polyethylene (PE) chains up to C150H302 and their binary mixtures with n-C13H28 are performed employing a united atom model. We estimate the surface tension values of PE melts from the atomic virial tensor over a range of temperatures, which are in good agreement with experimental results. Compared with short n-alkane systems, there is an enhanced surface segregation of methyl chain ends in longer PE chains. Moreover, the methyl groups become more segregated in the surface region with decreasing temperature, leading to the conclusion that the surface-segregation of methyl chain ends mainly arises from the enthalpic origin attributed to the lower cohesive energy density of terminal methyl groups. In the mixtures of two different chain lengths, the shorter chains are more likely to be found in the surface region, and this molecular segregation in moderately asymmetric mixtures in the chain length (C13H28 + C44H90) is dominated by the enthalpic effect of methyl chain ends. Such molecular segregation is further enhanced and dominated by the entropic effect of conformational constraints in the surface for the highly asymmetric mixtures containing long polymer chains (C13H28 + C150H3020). The estimated surface tension values of the mixtures are consistent with the observed molecular segregation characteristics. Despite this molecular segregation, the normalized density of methyl chain ends of the longer chain is more strongly enhanced, as compared with the all-segment density of the longer chain itself, in the surface region of melt mixtures. In addition, the molecular segregation results in higher order parameter of the shorter-chain segments at the surface and deeper persistence of surface-induced segmental order into the film for the longer chains, as compared with those in neat melt films.

scholarly journals Determining the composition of the vacuum–liquid interface in ionic-liquid mixtures

2018 ◽  
Vol 206 ◽  
pp. 497-522 ◽  
Author(s):  
E. J. Smoll ◽  
M. A. Tesa-Serrate ◽  
S. M. Purcell ◽  
L. D’Andrea ◽  
D. W. Bruce ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Ionic Liquid ◽  
Molecular Dynamics Simulations ◽  
Liquid Mixtures ◽  
Liquid Interface ◽  
Liquid Interfaces ◽  
Dynamics Simulations

The vacuum–liquid interfaces of a number of ionic-liquid mixtures have been investigated using a combination of RAS-LIF, selected surface tension measurements, and molecular dynamics simulations.

Understanding Physical Chemistry of BaxSr1-xTiO3 using ReaxFF Molecular Dynamics Simulations

2021 ◽  
Author(s):  
Dooman Akbarian ◽  
Nadire Nayir ◽  
Adri C. T. van Duin
Keyword(s):  
Physical Chemistry ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Strontium Titanate ◽  
Barium Strontium Titanate ◽  
Ferroelectric Properties ◽  
Barium Strontium ◽  
Dynamics Simulations

Barium strontium titanate BaxSr1−xTiO3 (BSTO) has been widely used in nano devices due to its unique ferroelectric properties and can be epitaxially grown on SrTiO3 (STO) support, with a reduced...

scholarly journals Model HULIS compounds in nanoaerosol clusters – investigations of surface tension and aggregate formation using molecular dynamics simulations

2011 ◽  
Vol 11 (13) ◽  
pp. 6549-6557 ◽  
Author(s):  
T. Hede ◽  
X. Li ◽  
C. Leck ◽  
Y. Tu ◽  
H. Ågren
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Molecular Dynamics Simulations ◽  
Cloud Condensation Nuclei ◽  
Chemical Properties ◽  
Droplet Growth ◽  
Dynamics Simulations ◽  
Pinic Acid ◽  
Vapour Condensation ◽  
And Chemical Properties

Abstract. Cloud condensation nuclei act as cores for water vapour condensation, and their composition and chemical properties may enhance or depress the ability for droplet growth. In this study we use molecular dynamics simulations to show that model humic-like substances (HULIS) in systems containing 10 000 water molecules mimic experimental data well referring to reduction of surface tension. The model HULIS compounds investigated in this study are cis-pinonic acid (CPA), pinic acid (PAD) and pinonaldehyde (PAL). The structural properties examined show the ability for the model HULIS compounds to aggregate inside the nanoaerosol clusters.

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