We used classical molecular dynamics simulation with the DREIDING force field to characterize changes in nanostructure of Nafion membrane brought about by systematically changing hydration level. calculated relative percentages free, weakly bound, and bound water hydrated membranes. At low levels, coordination hydronium ions multiple sulfonate groups prevents vehicular transport impedes structural protons through steric hindrance ions. Our results provide insights into are excellent...

The effects of hydration level and temperature on the nanostructure an atomistic model a Nafion (DuPont) membrane vehicular transport hydronium ions water molecules were examined using classical molecular dynamics simulations. Through determination analysis structural dynamical parameters such as density, radial distribution functions, coordination numbers, mean square deviations, diffusion coefficients, we identify that play important role in modifying structure near sulfonate groups. In...

We have performed a detailed and comprehensive analysis of the dynamics water molecules hydronium ions in hydrated Nafion using classical molecular simulations with DREIDING force field. In addition to calculating diffusion coefficients as function hydration level, we also determined mean residence time H(2)O H(3)O(+) first solvation shell SO(3)(-) groups. The coefficient increases increasing level is good agreement experiment. decreases membrane from 1 ns at low 75 ps highest studied. These...

We have performed a detailed analysis of water clustering and percolation in hydrated Nafion configurations generated by classical molecular dynamics simulations. Our results show that at low hydration levels H2O molecules are isolated continuous hydrogen-bonded network forms as the level is increased. quantitative has established (λ) between 5 6 H2O/SO3− threshold Nafion. also examined effect such on proton transport studying structural diffusion protons using quantum hopping method. The...

Polyoligomeric silsesquioxane (POSS) tailored with trifluoromethanesulfonylimide‐lithium and solvated in tetraglyme (G4) is a potential electrolyte for Li‐ion batteries. Using classical MD simulations, at different G4/POSS(–LiNSO2CF3)8 molar ratios, the interactions of Li+ ions oxygen atoms G4 and, oxygen/nitrogen sites pendant tails, behavior POSS(–‐NSO2CF3)8 anion, mobility species are investigated. The RDFs showed that there exist competing O(G4), O(POSS), N(POSS) ions. lifetime analysis...

The sI methane clathrate hydrate consists of gas molecules encapsulated as dodecahedron (512CH4) and tetrakaidecahedron (51262CH4) water cages. characterization the stability these cages is crucial to an understanding mechanism their formation. In present work, we perform calculations using density functional theory calculate interaction energies, free reactivity indices contributions from polarization functions energies more than diffuse Pople basis sets, though both correlation-consistent...

Perfluorosulfonic acid (PFSA) polymer electrolyte membranes like Dow, Aciplex and Nafion have similar backbones but different side chain pendants. The effect of hydration temperature on the pendant nanostructure, water hydronium ion dynamics, are investigated by employing classical molecular dynamics simulations at 300 K 350 K. 60% longer length in compared to Dow results phase segregation. presence an extra ether oxygen atom provides more flexibility (∼20% contraction caused hydrophobic...

We describe a multireference configuration interaction method that takes advantage of local correlation methods in both the internal (originally occupied) and external unoccupied or virtual) orbital spaces. In space, implementation is trivial involves neglecting configurations having simultaneous excitations out widely separated orbitals. restricting space allowed correlating orbitals to those localized near hole Of course, this necessitates use virtual which turn requires one sacrifice...

We recently developed a reduced scaling multireference configuration interaction (MRCI) method based on local correlation in the internal (occupied) and external (virtual) orbital spaces. This technique can be used, e.g., to predict bond dissociation energies large molecules with reasonable accuracy. However, inherent lack of size extensivity truncated CI is disadvantage that principle worsens as system grows. Here we implement an priori size-extensive modification MRCI known averaged...

This paper details the multiscale methodology developed to analyze formation of nanoparticles in a manner that makes it possible follow evolution structures chemically specific way. The atomistic model for particle inception code combines strengths kinetic Monte Carlo and molecular dynamics is used study chemical physical properties generated premixed fuel-rich benzene flame, providing scale (bonds, bond angles, dihedral angles) as soot precursors evolve into three-dimensional structure....

In this study, we examine the effect of various anions and temperature on structure dynamics 1-hexyl-3-methylimidazolium ionic liquids (ILs) from molecular simulations. The structural properties show that ILs containing smaller like Cl– Br– are relatively higher cation–anion interactions, compared to larger OTf– NTf2–. all ILs, spatial distribution is closer acidic hydrogen atom cation two nonacidic atoms cation. diffusion coefficients cations (ionic conductivity) increase with anionic size....

Aciplex is a perfluorosulfonic acid (PFSA) polymer electrolyte membrane, where its efficiency depends on hydration and temperature. In the present work, nanostructure of membrane transport hydronium ions water molecules are characterized using classical molecular dynamics simulations at varying hydrations temperatures. An examination radial distribution functions scattering intensities shows that temperature has negligible effect all levels. The calculated structural factors closely resemble...

The sI type methane clathrate hydrate lattice is formed during the process of nucleation where gas molecules are encapsulated in form dodecahedron (512CH4) and tetrakaidecahedron (51262CH4) water cages. characterization change vibrational modes which occur on encapsulation CH4 these cages plays a key role understanding formation subsequent growth to lattice. In this present work, we have chosen density functional theory (DFT) using dispersion corrected B97-D characterize Raman frequency...

Phosphoric acid doped polybenzimidazole is promising electrolyte membranes for high temperature (100 °C and above) fuel cells. Proton conduction governed by the amount of phosphoric content in polymer membrane. In this present work, we perform molecular dynamics simulations on 2-phenyl-1H,1'H-5,5'-bibenzo[d]imidazole (monomer unit polybenzimidazole) to characterize structural dynamical properties at varying temperature. From analysis, have predicted arrangement acids, formation H-bonds...

A molecular investigation on the effect of water structural properties imidazolium-based ionic liquids (ILs) is essential due to its various industrial applications. In this work, we employ dynamics simulations characterize influence concentrations nanostructural 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Hmim][NTf2] IL. An examination interactions in IL-water mixtures shows following trends: (a) At low concentration, small regions molecules are surrounded by several...

Hydrogen bonding in imidazole plays a key role proton conduction and rotation of an molecule the process results cleavage hydrogen bonds between molecules. In present work, we characterize transport energy barriers chains by density functional theory. Our calculations show that propagation excess along chain requires crossing barriers, lower than 1 kcal/mol. The presence has stronger effect on immediate neighboring molecules, is negligible after two subsequent all molecules transfer first...

Glyme-based sodium electrolytes show excellent electrochemical properties and good chemical thermal stability compared with existing carbonate-based battery electrolytes. In this investigation, we perform classical molecular dynamics (MD) simulations to examine the effect of concentration temperature on ion-ion interactions ion-solvent via radial distribution functions (RDFs), mean residence time, ion cluster analysis, diffusion coefficients, ionic conductivity in hexafluorophosphate (NaPF6)...

Triflic acid is a functional group of perflourosulfonated polymer electrolyte membranes where the sulfonate responsible for proton conduction. However, even at extremely low hydration, triflic exists as triflate ion. In this work, we have developed force-field and ion by deriving parameters using ab initio calculations incorporated these with Optimized Potentials Liquid Simulations - All Atom (OPLS-AA) force-field. We employed classical molecular dynamics (MD) simulations force field to...

Ionic-liquid-doped perfluorosulfonic acid membranes (PFSA) are promising electrolytes for intermediate/high-temperature fuel cell applications. In the present study, we examine proton-transport pathways in a triethylammonium-triflate (TEATF) ionic liquid (IL)-doped Nafion membrane using quantum chemistry calculations. The IL-doped matrix contains triflic (TFA), triflate anions (TFA(-)), triethylamine (TEA), and triethylammonium cations (TEAH(+)). Results show that proton abstraction from...

The time-scale and site preferential interaction of CO₂ absorption in tetra-butylphosphonium lysinate amino acid ionic liquid is examined using molecular dynamics simulations.

The annealing of polymer electrolyte membranes is known to affect the membrane structure and proton conductivity. observed changes depend drastically upon temperatures cooling rates. In this study, we have performed a fully atomistic classical molecular dynamics simulation hydrated Nafion at various hydration levels simulations show compression hydrophobic domains by larger water clusters, with strong antiplasticization effect hydration, demonstrated increasing glass-transition temperature....

Hydrogen clathrate hydrates are promising sources of clean energy and known to exist in a sII hydrate lattice, which consists H2 molecules dodecahedron (512) hexakaidecahedron (51264) water cages. The formation these occur extreme thermodynamic conditions is be considerably reduced by an inclusion tetrahydrofuran (THF) cages lattice. In this present work, we employ the density functional theory with dispersion corrected (B97-D) characterize vibrational Raman modes pure THF doped hydrogen...