The mechanisms of lithium cation (Li+) and bis(trifluoromethane)sulfonamide anion (TFSI-) transport in poly(ethylene oxide) (PEO, Mw = 2380) melts were examined using molecular dynamics (MD) simulations over a wide range salt concentrations temperatures. MD quantum-chemistry-based many-body polarizable force field yielded ion self-diffusion coefficients, electrolyte conductivity, aggregation, the coordination environment Li+ good agreement with experiment. Lithium was found to arise from...

Molecular dynamics simulation studies of the structure and differential capacitance (DC) for ionic liquid (IL) N-methyl-N-propylpyrrolidinium bis(trifluoromethane)sulfonyl imide ([pyr13][TFSI]) near a graphite electrode have been performed as function temperature potential. The IL exhibits multilayer that extends 20−30 Å from surface. composition ion orientation in innermost layer were found to be strongly dependent on While at potentials potential zero charge (PZC), both cations anions...

Quantum chemistry studies of ethylene carbonate (EC) and dimethyl (DMC) complexes with Li+ LiPF6 have been conducted. We found that complexation significantly stabilizes the highly polar cis−trans DMC conformation relative to nearly nonpolar gas-phase low energy cis−cis conformer. As a consequence, binding EC in gas phase is not as favorable previously reported. Furthermore, quantum reveal that, when ion pairs considered, DMC/LiPF6 complex about 1 kcal/mol more stable than EC/LiPF6 complex....

We present here an optimized united atom model that is able to reproduce properties of melts n-alkane chains varying molecular weights. This differs from previous models in the Lennard-Jones well depth for terminal methyl group (0.2264 kcal/mol) methylene units (0.093 kcal/mol). The position minimum at 4.5 Å both units. Properties n-C44H90 this are compared with experiments and those explicit model. Good agreement experiment obtained static melt, specifically P–V–T behavior, chain...

Molecular dynamics (MD) simulations have been performed on N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (mppy(+)TFSI(-)) and N,N-dimethyl- pyrrolidinium (mmpy(+)TFSI(+)) ionic liquids (ILs) doped with 0.25 mol fraction LiTFSI salt at 303-500 K. The liquid density, ion self-diffusion coefficients, conductivity predicted by MD were found to be in good agreement experimental data, where available. reveal that the Li(+) environment is similar mppy(+)TFSI(-) mmpy(+)TFSI(+)...

We have performed a detailed quantum chemistry study of the gas-phase benzene dimer. Large atomic orbital basis sets with multiple polarization functions were used. The effects set size, electron correlation, and superposition error investigated for low-energy planar sandwich (D6h C6v), parallel displaced (C2h), T-shaped (C2v) dimer structures. Our studies indicate that C2h-symmetry geometry is lowest-energy structure was found to be saddle point interconversion between structures, while on...

We have carried out molecular dynamics simulations of model polymer–nanoparticle composites (PNCs) consisting coarse-grained bead-necklace polymer chains and roughly spherical nanoparticles comprised like beads for the purpose gaining understanding influence nanoparticle–polymer interface on viscoelastic properties PNCs. The dynamic shear modulus Gc(t) viscosity ηc PNCs were determined as a function nanoparticle volume fraction, specific interfacial area, nature interaction. well described...

Energy-filtered transmission electron microscopy (EFTEM) was used to determine the distribution of lithium ions in solid polymer electrolytes for batteries. The interest are mixtures bis(trifluoromethane)sulfonimide salt and symmetric poly(styrene-block-ethylene oxide) copolymers (SEO). In contrast current liquid electrolytes, conductivity SEO/salt increases with increasing molecular weight copolymers. EFTEM results show that is increasingly localized middle poly(ethylene (PEO) lamellae as...

Molecular dynamics (MD) simulations were performed on N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (mppy+TFSI-) from 303 to 393 K improve understanding of the structure and ion transport this ionic liquid. The density, self-diffusion coefficients, conductivity, viscosity mppy+TFSI- predicted MD are in good agreement with experimental measurements. time-dependent shear modulus liquids was calculated compared that for nonionic liquids. On average each mppy+ cation found be...

Atomistic simulations were used to calculate the isothermal elastic properties for β-, α-, and δ-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The room-temperature isotherm each polymorph was computed in pressure interval 0⩽p⩽10.6 GPa extract initial bulk modulus Ko its derivative using equations of state employed previously experimental studies β-HMX isotherm. complete tensor calculated at room temperature atmospheric pressure. For case β-HMX, is compared one based on a fit sound...

The molecular geometries and conformational energies of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) 1,3-dimethyl-1,3-dinitro methyldiamine (DDMD) have been determined from high-level quantum chemistry calculations used in parametrizing a classical potential function for simulations HMX. Geometry optimizations HMX DDMD rotational energy barrier searches were performed at the B3LYP/6-311G** level, with subsequent single-point MP2/6-311G** level. Four unique low-energy conformers...

Molecular dynamics (MD) simulations of an electrolyte comprised ethylene carbonate (EC), dimethyl (DMC), and LiPF6 salt near the basal face graphite electrodes have been performed as a function electrode potential. Upon charging electrodes, less polar DMC molecule is partially replaced in interfacial layer by more EC. At negative potentials, carbonyl groups from molecules are repelled surface, while at positive we find substantial enrichment surface with groups. PF6– rapidly accumulates...

The oxidative decomposition mechanism of the lithium battery electrolyte solvent propylene carbonate (PC) with and without PF(6)(-) ClO(4)(-) anions has been investigated using density functional theory at B3LYP/6-311++G(d) level. Calculations were performed in gas phase (dielectric constant ε = 1) employing polarized continuum model a dielectric 20.5 to implicitly account for effects. It found that presence significantly reduces PC oxidation stability, stabilizes PC-anion products, changes...

Molecular dynamics (MD) simulations using a many-body polarizable force field were performed on ethylene carbonate (EC) doped with lithium bistrifluoromethanesulfonamide (LiTFSI) salt as function of temperature and concentration. At 313 K Li+ was coordinated by 2.7-3.2 EC carbonyl oxygen atoms 0.67-1.05 TFSI- at EC:Li = 10 20 concentrations. In completely dissociated electrolytes, however, solvated approximately 3.8 from average. The probability ions to participate ion aggregates decreased...

The pulsed-field-gradient spin-echo NMR measurements have been performed on 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([emim][FSI]) and [bis[(trifluoromethyl)sulfonyl]imide] ([emim][TFSI]) over a wide temperature range from 233 to 400 K. Molecular dynamics (MD) simulations [emim][FSI], [emim][TFSI], [N-methyl-N-propylpyrrolidinium][FSI] ([pyr(13)][FSI]), [pyr(13)][TFSI] utilizing many-body polarizable force field. An excellent agreement between the ion self-diffusion coefficients...

This contribution considers recent developments in the computer modelling of amorphous polymeric materials. Progress our capabilities to build models for simulation polymers from detailed atomistic scale up coarse-grained mesoscopic models, together with ever-improving performance computers, have led important insights simulations into structural and dynamic properties polymers. Structurally, chain connectivity introduces a range length scales that chemical bond radius gyration polymer...

Molecular dynamics simulations were performed on N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)imide (pyr(13)FSI) room temperature ionic liquid (RTIL) confined between graphite electrodes as a function of applied potential at 393 and 453 K using an accurate force field developed in this work. The electric double layer (EDL) structure differential capacitance (DC) pyr(13)FSI was compared with the results previous study similar RTIL pyr(13)bis(trifluoromethanesulfonyl)imide (pyr(13)TFSI)...

To investigate the implications of unique properties fullerenes on their interaction with and passive transport into lipid membranes, atomistic molecular dynamics simulations a C60 fullerene in fully hydrated di-myristoyl-phoshatidylcholine membrane have been carried out. In these free energy diffusivity were obtained as function its position within membrane. These utilized to calculate permeability through Simulations reveal that decreases passes from aqueous phase, head group layer...

Molecular simulations reveal that the shape of differential capacitance (DC) versus electrode potential can change qualitatively with structure surface. Whereas atomically flat basal plane graphite in contact a room-temperature ionic liquid generates camel-shaped DC, corrugated prismatic face same electrolyte exhibits bell-shaped behavior and much larger DCs at low double-layer potentials. The observed DC was correlated structural changes occurring double layer as function applied potential....

We have conducted quantum chemistry calculations and gas- solution-phase reactive molecular dynamics simulation studies of reactions involving the ethylene carbonate (EC) radical anion EC(-) using force field ReaxFF. Our reveal that substantial barrier for transition from closed (cyclic) form, denoted c-EC(-), to linear (open) o-EC(-), results in a relatively long lifetime c-EC(-) allowing this compound react with other singly reduced alkyl carbonates. Using ReaxFF, we systematically...

The dependence on electrode potential of the interfacial structure and differential capacitance (DC) for 1-alkyl-3-methyimidazolium bis(trifluoromethanesulfonyl)imide ([Cnmim][TFSI], n = 2, 4, 6, 8) ionic liquids (IL) near basal (flat) prismatic edge face (rough) graphite electrodes was investigated here with atomistic simulations. Overall camel-shaped DCs were observed both surfaces. generated systematically larger capacitances than atomically flat face. Although DC is almost constant at...

Classical many-body polarizable force fields were developed for n-alkanes, perflouroalkanes, polyethers, ketones, and linear cyclic carbonates on the basis of quantum chemistry dimer energies model compounds empirical thermodynamic liquid-state properties. The dependence electron correlation contribution to binding energy basis-set size level theory was investigated as a function molecular separation number alkane, ether, ketone dimers. Molecular dynamics (MD) simulations accurately...

Molecular dynamics simulations of N-methyl-N-propylpyrrolidinium (pyr(13)) bis(trifluoromethanesulfonyl)imide (Ntf(2)) ionic liquid [pyr(13)][Ntf(2)] mixed with [Li][Ntf(2)] salt have been conducted using a polarizable force field. Mixture lithium mole fractions between 0% and 33% at 363 423 K yield densities, ion self-diffusion coefficients, conductivities in very good agreement available experimental data. In all investigated electrolytes, each Li(+) cation was found to be coordinated, on...

Dispersing nanoparticles in a polymer matrix is intrinsically challenging because of unfavorable entropic interactions between the and nanoparticle. Similar to suspensions larger colloidal particles, it has been found that thermodynamically stable dispersions can be achieved matrices when are decorated with dense layers tethers whose molecular weight comparable or greater than matrix. Utilizing dynamics simulations, we demonstrate that, contrast repulsive tethered polymers much shorter...