Neutral Pairs Research Articles

Effect of Correlated Pair Mutations in Protein Misfolding.

A Monte Carlo simulation based sequence design method is proposed to explore the effect of correlated pair mutations in proteins. In the designed sequences, the most correlated residue pairs are identified and mutated with all possible amino acid pairs except those already present. The cumulative correlated pair mutations generated an array of mutated sequences. Results show a significant increase in the probability of misfolding for correlated pair mutations as compared to that of the random pair mutations. The pair mutations of correlated residues that are in contact record a higher probability of misfolding as compared to the correlated residues that are not in contact. The probability of misfolding increases on pair mutation of nonlocally correlated residue pairs as compared to that of the locally correlated residue pairs. The choice of a compact or expanded conformation does not depend on the type of correlated pair mutations. Pair mutation of the most correlated residue pairs at the surface with hydrophobic amino acids results in higher misfolding probability as compared to that in the core. An exactly opposite behavior is observed on pair mutation with hydrophilic and charged amino acid pairs. The neutral amino acid pairs do not differentiate between core and surface sites. This study may be used for targeted mutation experiments to predict complex mutation patterns, reengineer the existing proteins, and design new proteins with reduced misfolding propensity.

Relative stability of planar clusters B11, B12, and B13 in neutral- and charged-states

Theoretically, within the diatomic model, there is studied the relative stability of most abundant boron clusters B11, B12, and B13 with planar structures in neutral, positively and negatively charge-states. According to the specific (pet atom) binding energy criterion, B12+ (6.49 eV) is found to be the most stable boron cluster, while B11– + B13+ (5.83 eV) neutral pair is expected to present the preferable ablation channel for boron-rich solids. Obtained results would be applicable in production of boron-clusters-based nanostructured coating materials with super-properties such as lightness, hardness, conductivity, chemically inertness, neutron-absorption, etc. making them especially effective for protection against cracking, wear, corrosion, neutron- and electromagnetic-radiations, etc.

Equilibrium Structure, Hydrogen Bonding, and Proton Conductivity in Half-Neutralized Diamine Ionic Liquids.

Recent experiments on proton conducting ionic liquids point to half-neutralized diamine-triflate salts as promising candidates for applications in power generation and energy conversion electrochemical devices. Structural and dynamical properties of the simplest among these compounds are investigated by a combination of density functional theory (DFT) and molecular dynamics (MD) simulations based on an empirical force field. Three different cations have been considered, consisting of a pair of amine-ammonium terminations joined by a short aliphatic segment -(CH2) n- with n = 2, 3, and 4. First, the ground state structure, vibrational eigenstates, and hydrogen-bonding properties of single ions, neutral ion pairs, small neutral aggregates of up to eight ions, and molecularly thin hydrogen bonded wires have been investigated by DFT computations. Second, structural and dynamical properties of homogeneous liquid and amorphous phases are investigated by MD simulations over the temperature range of 200 ≤ T ≤ 440 K. Structure factors, radial distribution functions, diffusion coefficient, and electrical conductivity are computed and discussed, highlighting the inherent structural heterogeneity of these compounds. The core investigation, however, is the characterization of connected paths consisting of cation chains that could support proton transport via a Grotthuss-type mechanism. Since simulations are carried out using a force field of fixed bonding topology, this analysis is based on the equilibrium structure only, using geometrical criteria to identify potential paths for proton conduction. Paths of connected cations can reach a length of 80 cations and 30 Å, provided that bridging oxygen atoms from triflate anions are taken into account. The effects of water contamination at 1% weight concentration on the structure, dynamics, and paths for proton transport are discussed.

Dimer neutral ion pairs and associative ions in saturated vapor of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid

In the temperature range of 388–506 K in saturated vapor over 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMImTfO) ionic liquid along with the monomer neutral ionic pairs (NIP) C+A–, where C+ is EMIm+ (cation) and A– is TfO– (anion), the dimers (C+A–)2 were registered with a fraction of 0.5% for the first time. The corresponding associative ions C2A+ and C3A2+ formed as a result of attachment of the cation C+ to the monomer and dimer NIPs were also found. The evaporation enthalpies ΔvH°(298.15 K) = 128 ± 5 kJ mol–1 (monomer) and ΔvH°(298.15 K) = 161 ± 9 kJ mol–1 (dimer) were determined. The enthalpy of formation of the monomer and dimer NIP of EMImTfO at 298.15 K in the state of ideal gas were derived from the evaporation enthalpies: –1033 ± 50 kJ mol–1 and –2160 ± 50 kJ mol–1, respectively. The desorption enthalpies ΔdesH°(T) of the C+, C2A+, and C3A2+ cations were found to be 164 ± 5 kJ mol–1 (435 K), 159 ± 7 kJ mol–1 (435 K), and 152 ± 21 kJ mol–1(457 K), respectively. The equilibrium constants of the heterophase ion-molecular reactions were measured and the formation enthalpies of associative ions were calculated: ΔfH°(C2A+, 298.15 K) = –493 ± 50 kJ mol–1 and ΔfH°(C3A2+, 298.15 K) = –1631 ± 50 kJ mol–1.

Modeling Transport Properties in Concentrated Systems Considering Species Association

Species association – including effects such as ion pairing and solvent complexation – can complicate electrochemical transport dynamics. As a liquid electrolyte becomes more concentrated, driving forces for association become stronger and may profoundly impact system performance. Ion pairing has been proposed to explain the extended diffuse double layers observed at ionic-liquid/electrode interfaces [1]. Researchers also have justified the low or negative cation transference numbers observed for many lithium electrolytes by suggesting that ions associate [2]. These discussions motivated our systematic study of species association effects in concentrated electrolytes. The Nernst–Planck theory has been used to study reactive multi-species liquid electrolytes [3], but it ignores solute/solute interactions, limiting applicability to dilute solutions [4]. In concentrated solutions, such interactions can alter transport dynamics substantially, even when species concentrations are relatively low. Monroe has illustrated that interactions between lithium salts and dissolved oxygen can manifest diffusion potentials that change open-circuit voltages of metal-air batteries considerably [5]. Accordingly, even the minor species produced by weak association should not be ignored in concentrated electrolytes. A multi-species concentrated-solution model considering species association will provide a more general and comprehensive interpretation of experimental transport-property data. Monroe and Delacourt derived flux-explicit transport laws from Onsager–Stefan–Maxwell equations, and emphasized the need for thermodynamic rigor in multi-species transport characterization [6]. The present research advances their framework further, by accounting for species association. In systems were species associate, the Onsager–Stefan–Maxwell transport equations are further constrained by local association equilibria and kinetics. Thus some transport properties may be intrinsically correlated. We will present reformed flux-explicit transport equations and clarify how locally equilibrated association affects apparent transport dynamics. Three systems, namely, doped ion-conductive ceramics, ionic liquids, and binary solutions, will be analyzed: we will investigate carrier/carrier interaction in doped solid electrolytes, and illustrate how defects or doped elements induce diffusion polarization; we will model the ionic-liquid double layer in cases where ions can combine to form a neutral pair; and we will discuss how the association of solutes affects transference-number measurements in liquid binary solutions. [1] M.A. Gebbie, et al., PNAS. 110, 9674-9679 (2013) [2] G. Richardson, et al., J. Electrochem. Soc., 165(9), H561-H567 (2018) [3] S. Clark, et al., ChemSusChem,10, 4735 – 4747 (2017) [4] A.M. Bizeray, et al., J. Electrochem. Soc., 163(8), E223-E229 [5] C. W. Monroe, J. Electrochem. Soc., 164(11), E3547-E3551 (2017) [6] C. W. Monroe and C. Delacourt, Electrochimica Acta, 114, 649–657 (2013)

Unexpectedly Large Decay Lengths of Double-Layer Forces in Solutions of Symmetric, Multivalent Electrolytes.

Double-layer forces acting between micron-sized silica particles are measured with the atomic force microscope in solutions of symmetric, multivalent electrolytes. In particular, the 2:2 electrolytes, CuSO4 and MgSO4, and the 3:3 electrolyte LaFe(CN)6 were investigated. For the multivalent electrolytes, the measured decay lengths are substantially larger than the ones expected on the basis of simple Debye-Hückel (DH) theory. These deviations can be explained quantitatively by the formation of neutral ion pairs. The measured surface charge density decreases in magnitude with increasing valence. Both effects are caused by ion-ion correlations, which are not included in the classical DH theory. However, this theory remains applicable, provided one considers the formation of ion pairs in solution and an effective surface charge density. This effective charge is substantially smaller in magnitude than the one of the bare surface. This reduction results from adsorption of counterions, which becomes stronger with increasing valence. These observations reveal that DH theory is applicable even in the presence of multivalent ions, provided the effective parameters are chosen appropriately.

Study of the emulsion droplet collisions with the polarizable water/1,2-dichloroethane interface by the open circuit potential measurements

The open circuit potential (OCP) measurements are used to study the single collisions of the DCE-in-water emulsion droplets containing an electrolyte (tetradodecylammonium chloride, TDDACl) with the polarizable water/1,2-dichloroethane (DCE) interface. The OCP transients exhibit a series of the potential spikes, which consist of the initial negative potential step followed by a slower relaxation of the potential to its original value. A novel mechanism of the collisions is proposed including the interpretation of the potential response shape. Low stability of the emulsion system precluded a convincing comparison of the OCP and DLS data, though in some cases the size distributions obtained by OCP and DLS measurements may coincide. A comparison of the interfacial tension or capacitance curves measured in the absence and presence of the emulsion droplets indicates that their specific adsorption at the water/DCE interface is negligible. The mean droplet diameter exhibits a monotonic increase with the increasing droplet concentration and time pointing to an increasing effect of the flocculation and coalescence. The change of the collision frequency with the emulsion droplet concentration can be rationalized by using a steady-state diffusion transport model, which predicts that the collision frequency scales down with the fourth power of the droplet diameter. The droplet size distribution is not much affected by a change in the TDDACl concentration, which leads to the proportional change of the total charge integrated from all the emulsion droplet collisions. However, the total charge itself represents only a small fraction of the charge theoretically available, which suggests that a large portion of the collisions are accompanied by the zero-net charge transfer of the neutral ion pair TDDA+Cl−, and/or a number of the droplets are lost through their accumulation on the glass walls of the experimental system. The DCE-in-water emulsion exhibits a very low stability, which is manifested primarily by a strong effect of the droplet concentration on the mean droplet diameter or by its increase with time, as well as by a difference in the droplet size distributions averaged over different time spans. Breakdown of this emulsion system seems to occur through a combination of the flocculation, coalescence and sedimentation. Nevertheless, the OCP measurements provide a valuable insight into its interfacial dynamic behavior.

The interaction between lithium acceptors and gallium donors in zinc oxide

Diffusion of lithium (Li) in uniformly gallium (Ga)-doped monocrystalline bulk zinc oxide (ZnO) is studied over a wide temperature range (500–1150°C) and is demonstrated to be dictated by the distribution of Ga. Below 800°C, the indiffusion of Li from a Li-doped ZnO sputtered film into n+ single crystalline ZnO yields an abrupt and compensated Li-doped box region with the Li concentration matching the free-electron concentration, in accordance with several previous experimental and theoretical reports. However, experimental observations of Li-diffusion at higher temperatures reveal a dissociative diffusion mechanism for heat treatments up to 1150°C. By employing a reaction-diffusion model that includes both Li and Ga, a dissociation energy of 4.6 eV is obtained from the experimental Li diffusion data. This is in excellent agreement with theoretical results for the dissociation of (LiZnGaZn)0 (4.8 eV) into Lii+ and (GaZnVZn)− and suggests that this neutral and stable acceptor-donor pair prevails in Li- and Ga-doped ZnO.

Test of discrete symmetries with neutral kaons at KLOE-2

The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) completed its data-taking at the e+e− DAΦNE collider, which is implementing an innovative collision scheme based on a crab-waist configuration, and achieving the integrated luminosity goal of more than 5 fb−1. KLOE-2 represents the continuation of KLOE with an upgraded detector and an extended physics program which includes neutral kaon interferometry and test of discrete symmetries among the main topics. Entangled neutral kaon pairs produced at DAΦNE are a unique tool to test discrete symmetries and quantum coherence at the utmost sensitivity, in particular strongly motivating the experimental searches of possible CPT violating effects, which would constitute an unambiguous signal of a New Physics framework. The status of the latest ongoing analyses on KLOE/KLOE-2 data using the most refined analyses tools will be presented and discussed: (i) search for CP violating KS→3π0 decay, (ii) measurement of the KS semileptonic charge asymmetry and tests of CP and CPT symmetry, (iii) test of Time reversal and CPT in transitions in ϕ→KSKL→πν, 3π0, (2π) decays.

The pH-dependence of lipid-mediated antimicrobial peptide resistance in a model staphylococcal plasma membrane: A two-for-one mechanism of epithelial defence circumvention

The mechanisms of membrane defence by lysylphosphatidylglycerol (LPG), were investigated using synthetic biomimetic mono- and bilayer models of methicillin resistant S. aureus ST239 TW, based on its lipid composition in both pH 7.4 (28% LPG) and pH 5.5 (51% LPG) cultures. These models incorporated a stable synthetic analogue of LPG (3adLPG) to facilitate long-duration biophysical studies, which were previously limited by the lability native LPG. Both increased 3adLPG content and full headgroup ionization at pH 5.5, increased bilayer order and dampened overall charge, via the formation of neutral ion pairs with anionic lipids. Ion pair formation in air/liquid interface lipid monolayers elicited a significant condensing effect, which correlated with the inhibition of subphase-injected magainin 2 F5W partitioning. In fluid phase lipid vesicles, increasing the proportion of 3adLPG from 28 to 51 mol% completely inhibited the adoption of the membrane-active α‑helical conformation of the peptide, without the need for full headgroup ionization. Neutron reflectivity measurements performed on biomimetic PG/3adLPG fluid floating bilayers, showed a significant ordering effect of mild acidity on a bilayer containing 30 mol% 3adLPG, whilst peptide binding/partitioning was only fully inhibited in a bilayer with 55 mol% 3adLPG at pH 5.5. These findings are discussed with respect to the roles of LPG in resistance to human epithelial defences in S. aureus and the continued evolution of this opportunistic pathogen's virulence.

Structural and optical properties of sulfur passivated epitaxial step-graded GaAs1-ySby materials

The impact of bulk and surface defect states on the vibrational and optical properties of step-graded epitaxial GaAs1-ySby (0 ≤ y ≤ 1) materials with and without chemical surface treatment by (NH4)2S was investigated. Tunable antimony (Sb) composition GaAs1-ySby epitaxial layers, grown by solid source molecular beam epitaxy (MBE), were realized on GaAs and Si substrates by varying key growth parameters (e.g., Sb/Ga flux ratio, growth temperature). Raman and photoluminescence (PL) spectroscopic analysis of (NH4)2S-treated GaAs1-ySby epitaxial layers revealed composition-independent Raman spectral widths and enhanced PL intensity (1.3×) following (NH4)2S surface treatment, indicating bulk defect-minimal epitaxy and a reduction in the surface recombination velocity corresponding to reduced surface defect sites, respectively. Moreover, quantification of the luminescence recombination mechanisms across a range of measurement temperatures and excitation intensities (i.e., varying laser power) indicate the presence of free-electron to neutral acceptor pair or Sb-defect-related recombination pathways, with detectable bulk defect recombination discernible only in binary GaSb PL spectra. In addition, PL analysis of the short- and long-term thermodynamic stability of sulfur-treated GaAs1-ySby/Al2O3 heterointerfaces revealed an absence of quantifiable atomic interdiffusion or native oxide formation. Leveraging the combined Raman and PL analysis herein, the quality of the heteroepitaxial step-graded epitaxial GaAs1-ySby materials can be optimized for optical devices.

LHC luminosity and energy upgrades confront natural supersymmetry models

The electroweak fine-tuning measure ${\mathrm{\ensuremath{\Delta}}}_{\mathrm{EW}}$ allows for correlated supersymmetry (SUSY) soft terms as are expected in any ultraviolet complete theory. Requiring no less than 3% electroweak fine-tuning implies upper bounds of about 360 GeV on all Higgsinos, while top squarks are lighter than $\ensuremath{\sim}3\text{ }\text{ }\mathrm{TeV}$ and gluinos are bounded by $\ensuremath{\sim}6--9\text{ }\text{ }\mathrm{TeV}$. We examine the reach for SUSY of the planned high luminosity (HL: $3\text{ }\text{ }{\mathrm{ab}}^{\ensuremath{-}1}$ at 14 TeV) and the proposed high energy (HE: $15\text{ }\text{ }{\mathrm{ab}}^{\ensuremath{-}1}$ at 27 TeV) upgrades of the LHC via four LHC collider search channels relevant for natural SUSY: 1. gluino pair production followed by gluino decay to third generation (s)quarks, 2. top squark pair production followed by decay to third generation quarks and light Higgsinos, 3. neutral Higgsino pair production with QCD jet radiation (resulting in monojet events with soft dileptons), and 4. wino pair production followed by decay to light Higgsinos leading to same-sign diboson production. We confront our reach results with upper limits on superpartner masses in four natural SUSY models: natural gravity mediation via the 1. two- and 2. three-extra-parameter nonuniversal Higgs models, 3. natural minilandscape models with generalized mirage mediation and 4. natural anomaly mediation We find that while the HL-LHC can probe considerable portions of natural SUSY parameter space in all these models, the HE-LHC will decisively cover the entire natural SUSY parameter space with better than 3% fine-tuning.

Proton Transfer in 1,2,4-Triazolium Dinitramide: Effect of Aqueous Microsolvation.

The gas phase proton transfer process in 1,2,4-triazolium dinitramide (TD) was studied using second-order perturbation theory to determine how the presence of one and two water molecules modifies the potential energy surface that connects the ion pair to the neutral pair. The presence of one water molecule can introduce small proton transfer energy barriers that separate the ion pair from the lower-energy neutral pair. These energy barriers are easily surmounted. Reaction paths were determined for single proton transfers and double proton transfers via one water molecule. In the presence of two water molecules, the global minimum is an ion pair, as are most of the lower-energy local minima. Energy barriers for single, double, and triple proton transfers were also found for TD in the presence of two water molecules. One TD ion pair structure with two water molecules has no corresponding neutral pair energy minimum. A quasi-atomic orbital analysis is used to understand the nature of the bonding in the various species studied in this work.

Smiles in face matching: Idiosyncratic information revealed through a smile improves unfamiliar face matching performance

Unfamiliar face matching is a surprisingly difficult task, yet we often rely on people's matching decisions in applied settings (e.g., border control). Most attempts to improve accuracy (including training and image manipulation) have had very limited success. In a series of studies, we demonstrate that using smiling rather than neutral pairs of images brings about significant improvements in face matching accuracy. This is true for both match and mismatch trials, implying that the information provided through a smile helps us detect images of the same identity as well as distinguishing between images of different identities. Study 1 compares matching performance when images in the face pair display either an open-mouth smile or a neutral expression. In Study 2, we add an intermediate level, closed-mouth smile, to identify the effect of teeth being exposed, and Study 3 explores face matching accuracy when only information about the lower part of the face is available. Results demonstrate that an open-mouth smile changes the face in an idiosyncratic way which aids face matching decisions. Such findings have practical implications for matching in the applied context where we typically use neutral images to represent ourselves in official documents.

Study of Salt Precipitation in Polymer Electrolytes Based on Poly(ethylene oxide) and EMImTf Ionic Liquid.

In solidlike polymer electrolytes, salt precipitation (SP) followed by the occurrence of neutral ion pairs in polymer electrolytes is known to deteriorate ionic conductivity, but has not been the subject of intense study so far. Here, the mechanism of SP is studied for a polymer electrolyte consisting of poly(ethylene oxide) (PEO) and ionic liquid salt of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMImTf), which is one of the promising prototype systems because of its technological relevance. It is found that Ångstrom-scale open spaces in the amorphous matrix sensitively change in response to the release of organic cation from PEO polymer chains as well as SP in the Arrhenius manner. The cation release, triggering off ion-pair formation, takes place at the temperature by far lower than that of SP with an activation energy of ∼0.2 eV, whereas SP involves an energy cost of ∼0.4 eV. The results suggest that SP in the PEO-EMImTf complex is mechanistically explained from the viewpoint of the abovementioned two processes, that is, cation release from the present PEO-EMImTf complex and ion pairing.

Tracking opinion convergence online

Abstract We investigate whether facial attractiveness, as one source of positive/negative attitudes towards one’s conversational partner, affects the degree and type of opinion convergence online, even in the absence of physical co-presence. Our hypothesis is that when you interact with someone you find attractive, opinion convergence will occur even if you are not physically co-present with them. Additionally, we tracked different types of opinion convergence (one-sided or mutual) and how convergence is linguistically negotiated in these different circumstances. Our hypothesis was confirmed, to a point. Opinion convergence was most frequent among Attracted pairs; however, opinion convergence was greatest among Neutral pairs. Opinion convergence was qualitatively different in the 3 conditions. This research adds to previous studies which highlighted aspects of communication unique to online environments (anonymity, invisibility) to explain the heightened tendency for face-threatening behaviours to occur online, by showing how implicit biases (operationalized here as facial attractiveness) can be an additional factor influencing online behaviour.

Relative stability of planar clusters B11, B12, and B13 in neutral- and charged-states

Theoretically, within the diatomic model, there is studied the relative stability of most abundant boron clusters B11, B12, and B13 with planar structures in neutral, positively and negatively charge-states. According to the specific (pet atom) binding energy criterion, B12+ (6.49 eV) is found to be the most stable boron cluster, while B11– + B13+ (5.83 eV) neutral pair is expected to present the preferable ablation channel for boron-rich solids. Obtained results would be applicable in production of boron-clusters-based nanostructured coating materials with super-properties such as lightness, hardness, conductivity, chemically inertness, neutron-absorption, etc. making them especially effective for protection against cracking, wear, corrosion, neutron- and electromagnetic-radiations, etc.

A first principle study of the phase stability, ion transport and substitution strategy for highly ionic conductive sodium antipervoskite as solid electrolyte for sodium ion batteries

Materials in the Na-rich antiperovskite family are promising candidates as solid electrolytes (SEs) for all-solid-state Na-ion batteries (NIBs). In this work, we carry out ab-initio calculations to study various properties of Na3OCl, namely the formation energies of various neutral defect pairs, the defect hopping barriers, the solution energies of high valence alkali earth metal substitutes to the Na atoms, and the effect of such substitution to the Na migration. While the introduction of alkali earth metal ions increases the Na vacancy concentration, the activation energy of Na transport also increases. Furthermore, we identify Ca as the most promising alkali earth metal to be doped into Na3OCl due to its low binding energy and relatively small impact on the migration barrier. Our work provides a theoretical framework for further improving the Na conductivity of materials in the antiperovskite family for all-solid-state NIBs.

Complexes of dipolar excitons in layered quasi-two-dimensional nanostructures

We discuss neutral and charged complexes (biexciton and trion) formed by indirect excitons in layered quasi-two-dimensional semiconductor heterostructures. Indirect excitons -- long-lived neutral Coulomb-bound pairs of electrons and holes of different layers -- have been known for semiconductor coupled quantum wells and are recently reported for van der Waals heterostructures such as bilayer graphene and transition metal dichalcogenides. Using the configuration space approach, we derive the analytical expressions for the trion and biexciton binding energies as functions of the interlayer distance. The method captures essential kinematics of complex formation to reveal significant binding energies, up to a few tens of meV for typical interlayer distances ~3-5 A, with the trion binding energy always being greater than that of the biexciton. Our results can contribute to the understanding of more complex many-body phenomena such as exciton Bose-Einstein condensation and Wigner-like electron-hole crystallization in layered semiconductor heterostructures.

Defect Chemistry and Lithium Transport in ANTI-Perovksite Superionic Conductors

Solid state electrolyte with fast lithium conduction is the core of the all-solid-state Li battery technology. By substituting the organic electrolyte with a piece of non-flammable ceramic material, we can achieve a better safety, a higher specific capacity and a higher energy density. To date, the major bottle neck for this technology is the slow bulk diffusion of solid state electrolyte and the interfacial incompatibility between the electrolyte and electrodes. To resolve these issues, several families of fast ionic conductors have been developed. The understanding of Li diffusion in these materials is essential to the development of novel family fast ionic conductors. In this sense, atomistic modeling provides us with a unique tool to obtain comprehensive information on the atom motion which is so far hard to access with experimental techniques. In this work, we use density functional theory (DFT) calculations as well as large scale classical molecular dynamics (MD) simulations to simulate the Li diffusion in a novel family of superionic conductor, lithium-rich anti-perovskites and provide an understanding of the Li diffusion behavior. Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10−3 S cm−1 at room temperature, among the highest reported values to date. We investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using DFT calculations and classical MD simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.