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Chemistry

Theoretical chemistry and modeling

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Displaying 126 - 150 of 194

Development and Validation of a Mechanism for Flame Propagation in R-32/Air Mixtures

March 6, 2018
Author(s)
Donald R. Burgess Jr., Jeffrey A. Manion, Robert R. Burrell, Valeri I. Babushok, Michael Hegetschweiler, Gregory T. Linteris
A mechanism for the combustion of the refrigerant R-32 (CH2F2) in air mixtures was developed and validated through comparisons with measured flame speeds for a range of equivalence ratios (0.9 to 1.4) and pressures (1 to 3 bar) using a constant-volume

Quantum for Pressure

January 5, 2018
Author(s)
Jay H. Hendricks, Patrick F. Egan, Jacob E. Ricker, Jack A. Stone Jr., Kevin O. Douglass, Gregory F. Strouse
A team of NIST scientists is working to fundamentally change the way that the unit of pressure is realized and disseminated, an effort that will lead to the elimination of mercury barometer pressure standards.

The Influence of the Aromaticity in the Gas Chromatography Retention: The Case of Polycyclic Aromatic Sulfur Heterocycles

December 15, 2017
Author(s)
Jorge O. Ona-Ruales, Yosadara Ruiz-Morales, Fernando Alvarez-Ramirez, Walter Brent Wilson, Stephen A. Wise
The aromaticity has been used as a criterion to explain the GC retention of cata-condensed polycyclic aromatic sulfur heterocycles (PASHs) C12H8S, C16H10S, C20H12S; and peri-condensed PASHs C18H10S, in a GC column with 50% phenyl / 50% methyl silphenylene

Free Surface Relaxations of Star-Shaped Polymer Films

November 28, 2017
Author(s)
Alexandros Chremos, Bradley R. Frieberg, Emmanouil Glynos, Kyle Johnson, Hengxi Yang, Suresh Narayanan, Peter F. Green, Georgios Sakellariou
X-ray photon correlation spectroscopy (XPCS) studies show that the viscosities of thin film linear chain polymers at temperatures sufficiently high above the bulk glass transition temperature Tg bulk are equal to the bulk zero shear viscosities. The free

Electrochemical capacitance of CO-terminated Pt(111) is dominated by CO-solvent gap

October 17, 2017
Author(s)
Ravishankar Sundararaman, Marta C. Figueiredo, Marc Koper, Kathleen Schwarz
The distribution of electric fields within the electrochemical double layer depends on both the electrode and electrolyte in complex ways. These fields strongly influence chemical dynamics in the electrode-electrolyte interface, but cannot be measured

Simulation-aided Correlations for the Dielectric Constant of H2S, SO2, and SF6

August 16, 2017
Author(s)
Allan H. Harvey, Raymond D. Mountain
A new method is developed for correlating the static dielectric constant of polar fluids over wide ranges of conditions where few experimental data exist. Molecular dynamics simulations are used to establish the temperature and density dependence of the

Temperature extrapolation of multicomponent grand canonical free energy landscapes

August 7, 2017
Author(s)
Nathan Mahynski, Jeffrey R. Errington, Vincent K. Shen
We derive a method for extrapolating the grand canonical free energy landscape of a multicomponent fluid system from one temperature to another. Previously, we introduced this statistical mechanical framework for the case where kinetic energy contributions

Connection between thermodynamics and dynamics of simple fluids in pores: impact of fluid-fluid interaction range and fluid-solid interaction strength

July 5, 2017
Author(s)
William P. Krekelberg, Daniel W. Siderius, Vincent K. Shen, Thomas M. Truskett, Jeffrey R. Errington
Using molecular simulations, we investigate how the range of fluid-fluid (adsorbate-adsorbate) interactions and the strength of fluid-solid (adsorbate-adsorbent) interactions impact the strong connection between distinct adsorptive regimes and distinct

Critical Evaluation of Thermodynamic Properties for Halobenzoic Acids Through Consistency Analyses for Results from Experiment and Computational Chemistry

June 14, 2017
Author(s)
Robert D. Chirico, Andrei F. Kazakov, Ala Bazyleva, Vladimir Diky, Kenneth Kroenlein, Vladimir N. Emel'yanenko, Sergey P. Verevkin
Thermodynamic properties of the twelve monohalobenzoic acids are critically evaluated through application of computational chemistry methods for the ideal-gas phase and thermodynamic consistency assessment of properties determined experimentally and

Thermodynamics of antiviral and antiparkinsonian drug amantadine hydrochloride: condensed state properties and decomposition

May 1, 2017
Author(s)
Ala Bazyleva, Andrey V. Blokhin, Dzmitry H. Zaitsau, Gennady J. Kabo, Yauheni Paulechka, Andrei F. Kazakov, John M. Shaw
Heat capacities of antiviral and antiparkinsonian drug amantadine hydrochloride in the crystalline state were measured by adiabatic and differential scanning calorimetry in the temperature range from (5 to 470) K. Two unresolved low-enthalpy solid-to-solid

Molecular Dynamics Simulation of Trimer Self-Assembly Under Shear

March 6, 2017
Author(s)
Raymond D. Mountain, Harold Hatch, Vincent K. Shen
The self-assembly of patchy trimer particles with one attractive bead and two repulsive beads is investigated with nonequilibrium molecular dynamics simulations in the presence of a velocity gradient, as would be produced by the application of a shear

Energy accommodation coefficient extracted from acoustic resonator experiments

November 2, 2016
Author(s)
Felix Sharipov, Michael R. Moldover
We review values of the temperature jump coefficient zeta_T determined from measurements of the acoustic resonance frequencies f_acoust of helium-filled and argon-filled, metal-walled, quasi- spherical cavities near ambient temperature. We combine these

A Compilation of Enthalpies of Formation for Hydrogen-Oxygen (HxOy) Species

March 11, 2016
Author(s)
Donald R. Burgess Jr.
In this work, we have compiled enthalpies of formation for nine hydrogen-oxygen species (HxOy) and selected values for use. The compilation consists of values derived from experimental measurements, quantum chemical calculations, and evaluations. This work

Adsorption, X-ray Diffraction, Photoelectron, and Atomic Emission Spectroscopy Benchmark Studies for the Eighth Industrial Fluid Properties Simulation Challenge

January 31, 2016
Author(s)
Daniel Siderius, Vincent K. Shen, Raymond D. Mountain, Richard B. Ross, David B. Aeschliman, Riaz Ahmad, John K. Brennan, Myles L. Brostrom, Kevin A. Frankel, Jonathan D. Moore, Joshua D. Moore, Derrick M. Poirier, Matthias Thommes, Nathan E. Schultz, Kenneth D. Smith
The primary goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. The challenge focused, in particular, on

The Eighth Industrial Fluid Properties Simulation Challenge

January 31, 2016
Author(s)
Daniel Siderius, Vincent K. Shen, Raymond D. Mountain, Nathan E. Schultz, Riaz Ahmad, John K. Brennan, Kevin A. Frankel, Jonathan D. Moore, Richard B. Ross, Matthias Thommes, Kenneth D. Smith
The goal of the eighth industrial fluid properties simulation challenge was to test the ability of molecular simulation methods to predict the adsorption of organic adsorbates in activated carbon materials. In particular, the eighth challenge focused on
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