A theory for site–site pair distribution functions of molecular fluids

1977 ◽  
Vol 67 (7) ◽  
pp. 3194-3205 ◽  
Author(s):  
Elijah Johnson
Keyword(s):  
Distribution Functions ◽  
Molecular Fluids ◽  
Pair Distribution Functions ◽  
Site Pair

Comparison of the Structure of Liquid Amides as Determined by Diffraction Experiments and Molecular Dynamics Simulations

1995 ◽  
Vol 50 (1) ◽  
pp. 38-50 ◽  
Author(s):  
Pia C. Schoester ◽  
Manfred D. Zeidler ◽  
Tamäs Radnai ◽  
Philippe A. Bopp
Keyword(s):  
Molecular Dynamics ◽  
Room Temperature ◽  
Heavy Atom ◽  
Distribution Functions ◽  
X Ray ◽  
Atom Pairs ◽  
Dynamics Simulations ◽  
Pair Distribution Functions ◽  
Flexible Models ◽  
Site Pair

The intermodular structures of liquid formamide, N-methylformamide and N,N-dimethylformamide at room temperature are studied by means of NVE molecular dynamics computer simulations. Newly developed flexible models are used. X-ray and neutron weighted structure and total radial pair distribution functions are computed from the simulated site-site pair distribution functions. They are compared with experimental results. The agreement is usually satisfactory as far as heavy atom pairs are concerned while the lengths of the hydrogen bonds are found to be systematically too long in the simulations.

scholarly journals Local structure and distortions of mixed methane-carbon dioxide hydrates

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Bernadette R. Cladek ◽  
S. Michelle Everett ◽  
Marshall T. McDonnell ◽  
Matthew G. Tucker ◽  
David J. Keffer ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Exchange Process ◽  
Carbon Dioxide Sequestration ◽  
Distribution Functions ◽  
Atomic Scale ◽  
Mixed Gas ◽  
Pure Compounds ◽  
Dynamics Simulations ◽  
Pair Distribution Functions ◽  
Methane Carbon

AbstractA vast source of methane is found in gas hydrate deposits, which form naturally dispersed throughout ocean sediments and arctic permafrost. Methane may be obtained from hydrates by exchange with hydrocarbon byproduct carbon dioxide. It is imperative for the development of safe methane extraction and carbon dioxide sequestration to understand how methane and carbon dioxide co-occupy the same hydrate structure. Pair distribution functions (PDFs) provide atomic-scale structural insight into intermolecular interactions in methane and carbon dioxide hydrates. We present experimental neutron PDFs of methane, carbon dioxide and mixed methane-carbon dioxide hydrates at 10 K analyzed with complementing classical molecular dynamics simulations and Reverse Monte Carlo fitting. Mixed hydrate, which forms during the exchange process, is more locally disordered than methane or carbon dioxide hydrates. The behavior of mixed gas species cannot be interpolated from properties of pure compounds, and PDF measurements provide important understanding of how the guest composition impacts overall order in the hydrate structure.

Molecular dynamics study of the hydrophobic 6,6-ionene oligocation in aqueous solution with sodium halides

2010 ◽  
Vol 82 (10) ◽  
pp. 1943-1955 ◽  
Author(s):  
Maksym Druchok ◽  
Vojko Vlachy
Keyword(s):  
Molecular Dynamics ◽  
Md Simulation ◽  
Distribution Functions ◽  
Low Molecular Weight ◽  
Specific Effects ◽  
Sodium Cations ◽  
Counter Ions ◽  
Sodium Halides ◽  
Explicit Water ◽  
Pair Distribution Functions

An explicit water molecular dynamics (MD) simulation is presented of a solution modeling aliphatic 6,6-ionene oligocations mixed with low-molecular-weight electrolytes. In all cases, the co-ions were sodium cations and the counterions were fluoride, chloride, bromide, or iodide anions. The simple point charge/extended (SPC/E) model was used to describe water. The results of the simulation at T = 278 K (the data for 298 K were obtained earlier) and T = 318 K are presented in the form of pair distributions between various atoms and/or between ions in the system. We were interested in how temperature variation modifies the ion-specific effects, revealed by the various pair distribution functions (PDFs). The results were compared with previous calculations for the less hydrophobic 3,3-ionene solutions. Simulations of 6,6-ionene solutions containing mixtures of fluoride and iodide counter-ions at T = 298 K were also presented.

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