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Simulation of Crystalline Nanoporous Materials and the Computation of Adsorption/Diffusion Properties
Published in T. Grant Glover, Bin Mu, Gas Adsorption in Metal-Organic Frameworks, 2018
The radial distribution function (RDF) describes the local structure and spatial correlation between molecules. It is a central quantity for studying and understanding fluids. The RDF function g(r) gives the probability of finding a pair of atoms a distance r apart, relative to the probability expected for a completely random distribution at the same density [55]. This normalization ensure that g(r→∞)=1. Properties like energy, pressure, and chemical potential can be expressed in terms of the RDF. For example, pressure can be computed from the derivative of the pair potential and from g(r) βp=ρ−βρ26∫0∞4πr3du(r)drg(r)dr.
Thermodynamic properties analysis of warm-mix recycled asphalt binders using molecular dynamics simulation
Published in Road Materials and Pavement Design, 2023
The Radial distribution function (RDF) characterises the normalised probability of a molecule occurring around the reference molecule at a certain radial distance. The RDF curves can be used to determine the morphological structure of the asphalt microscopic molecules and thus predict their thermodynamic and mechanical properties. The RDF can be calculated as follows: where ρ is the system density; δr is the interval distance; r is radial distance of the molecular system; N and ΔN are the total number of molecules and the number of molecules in the range from r to r + δr, respectively; and T is the simulation time.
Molecular dynamics study of salt effects on micellization of N-dodecyl-N,N-dimethyl-3-ammonio-1-propane-sulfonate
Published in Journal of Dispersion Science and Technology, 2018
Guangmiao Qu, Qi Guan, Haiyan Sun, Musen Lin, Yuan Cai, Yong Pan, Jie Li, Ruixia Niu
The effects between the micelle and salt ions can be understood by investigating the distribution of components at the micelle-water interface. Radial distribution function (RDF) describes how density varies as a function of distance from a reference particle (atoms, molecules, colloids, etc.). RDFs between different groups are used to elucidate the structure of micelle. Figure 4 shows RDFs of sulfo groups in the hydrophilic group -N+-(CH2)3- with hydrophobic tail end carbon, C, gSO-C1(r) represents the RDF. Maximum of gSO-C1(r) is located at 1.50 nm. This value can be taken as the radius of the micelle, and the results are close to the value of 1.62 nm by this method being done by A. D. Giampaolo[22] and in our previous studies[13]. Results show the same trends with the addition of NaCl and CaCl2, which indicates that the addition of NaCl and CaCl2 can’t change the structure of micelle. Figure 5 shows RDFs of water molecules with sulfo groups in the hydrophilic group -N+-(CH2)3-, and gSO-w(r) represents the RDF. The value of gSO-w(r) means the formation of strong hydrogen bonds of -N+-(CH2)3- with the hydrogen atom of water molecule[23]. This also indicates that the addition of NaCl and CaCl2 has little effects on the interactions between SB12-3 and water molecules.
Investigation on sub-to-supercritical transition of diesel: Gas–liquid interface properties
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Ruina Li, Liang Zhang, Yang Song, Chunyi Tang, Quan Hu
The radial distribution function (RDF) is an important physical quantity that characterizes the microstructure of a molecule. Its physical meaning refers to the probability density of another molecule at a distance r from a reference molecule in the fluid system, as shown in Figure 6 (Long, Micci, and Wong 1996). The calculation formula for the radial distribution function is as follows: