With the aid of molecular dynamics simulations, we study structure and different ionic liquid systems.

Abstract Multiphase reactions of ozone with human skin oils impact indoor air quality by depleting and forming semi-volatile organic compounds, which can be respiratory irritants. Here we demonstrate the clothing on composition exposure integrating chemistry modeling over a wide range different spatial temporal scales. Constrained molecular dynamics simulations that provide key kinetic parameters, model reproduces experimental measurements predicts squalene could persist in for several hours...

We performed classical molecular dynamics simulations to quantify and understand the nonreactive, dermal uptake of volatile organic compounds formed during ozonolysis human skin oils. Our results include surface accommodation coefficients, partitioning constants, bulk diffusivities, desorption lifetimes. These parameters were used improve constrain kinetic multilayer model chemistry (KM-SUB-Skin). By comparing common outputs (bulk coefficients), we cross-validate two approaches and, thus,...

Commonly found in atmospheric aerosols, cooking oils, and human sebum, unsaturated lipids rapidly decay upon exposure to ozone, following the Criegee mechanism. Here, gas-surface ozonolysis of three oleic acid-based compounds was studied a reactor indoors. Under dry conditions, quantitative product analyses by 1H NMR indicate up 79% molar yield stable secondary ozonides (SOZs) oxidized triolein methyl oleate coatings. Elevated relative humidity (RH) significantly suppresses SOZ yields,...

The oxidation of human sebum, a lipid mixture covering our skin, generates range volatile and semivolatile carbonyl compounds that contribute largely to indoor air pollution in crowded environments. Kinetic models have been developed gain deeper understanding this complex multiphase chemistry, but they rely partially on rough estimates kinetic thermodynamic parameters, especially those describing skin permeation. Here, we employ atomistic molecular dynamics simulations study the...

We present a first-principles calculation and mechanistic characterization of the ion product liquid water (K W ), based on Quantum Cluster Equilibrium (QCE) theory with variety ab initio density functional methods. The QCE method is T-dependent Boltzmann weighting different-sized clusters consequently enables observation thermodynamically less favored therefore low populated species such as hydronium hydroxide ions in water. find that common quantum chemical methods achieve...

We report on the development of a modelling consortium for chemistry in indoor environments that connects models over range spatial and temporal scales, from molecular to room scales sub-nanosecond days, respectively.

We study the structure and dynamics of water subject to a range static external electric fields, using molecular simulations. In particular, we monitor changes in hydrogen bond kinetics, reorientation dynamics, translational motions molecules. find that molecules translate rotate slower fields because tendency reinstate aligned orientation reduces probability finding new partner hence increases reforming already ruptured bonds. Furthermore, dipolar alignment with field results structural...

An extension of the quantum cluster equilibrium theory to treat binary mixtures is introduced in this work. The necessary equations are derived and a possible implementation presented. In addition an alternative sampling procedure using widely available experimental data for approach suggested tested. illustrative example, namely, mixture water dimethyl sulfoxide, given demonstrate new approach. A basic set containing relevant motifs. populations computed by compared data. Furthermore,...

We applied the binary Quantum Cluster Equilibrium (bQCE) method to a number of alkylammonium-based protic ionic liquids in order predict boiling points, vaporization enthalpies, and proton activities. The theory combines statistical thermodynamics van-der-Waals-type clusters with ab initio quantum chemistry yields partition functions (and associated thermodynamic potentials) mixtures over wide range phase points. Unlike conventional cluster approaches that are limited prediction properties,...

Treating the bulk phase with high-level ab initio methods, such as coupled cluster, is a nontrivial task because of computational costs these electronic structure methods. In this part our hydrogen fluoride study we make use quantum cluster equilibrium method, which employs input small clusters and combines it simple statistical mechanics in order to describe condensed phenomena. If no parameter adjustment applied, then lower chemical density functional theory conjunction generalized...

The investigation of liquid phases by means accurate electronic structure methods is a demanding task due to the high computational effort. We applied second-order Møller-Plesset perturbation theory and high-level quantum chemical calculations using coupled-cluster method with single, double perturbative triple excitations in combination Dunnings correlation-consistent basis sets up quintuple ζ quality. Based on these calculations, we extrapolated correlation energy set limit order improve...

We present an updated version of Peacemaker, a software package for performing neat and binary Quantum Cluster Equilibrium (QCE, bQCE) calculations. Peacemaker2 has been rewritten from scratch is fast, robust, parallelized, well-documented. Apart sketching the implementation introducing several improvements to bQCE theory, we calculate excess enthalpies mixing two selected amide–water mixtures give illustrative example application.

Simulations of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in an external electric field have been performed using a Drude particle polarizable force field. The structure ions has analyzed, with close attention paid to configurations ions. “charge arm” concept is used explain certain changes these that would be difficult rationalize otherwise, e.g., trans → cis isomerization anion and extension alkyl chain cation. It also shown orient themselves so their...

Abstract We demonstrate for formic and acetic acid dissolved in water as examples that the binary quantum cluster equilibrium (bQCE) approach can predict strengths over whole range of concentrations. The strength increases a complex rather than simple way with increasing mole fraction from 0 to 0.7, reflecting interplay between dissociated ions or conjugate bases available compared molecules. Furthermore, our calculated ion concentrations meet experimental maximum conductivity excellent...

Femtosecond two-dimensional infrared (2DIR) spectroscopy was carried out to study the dynamics of vibrational spectral diffusion nitrile stretching vibration thiocyanate anions (S-C≡N(-)) dissolved in liquid-to-supercritical heavy water (D2O). The 2DIR line shapes were used extract through a nodal slope analysis quantitative information about correlation function for temporal fluctuations CN-stretching frequency. inverse could be fitted phenomenologically by simple double-exponential decay...

The established quantum cluster equilibrium (QCE) approach is refined and applied to N-methylformamide (NMF) its aqueous solution. QCE method split into two iterative cycles: one which converges the liquid phase solution of equations another yields gas phase. By comparing Gibbs energies, thermodynamically stable at a given temperature pressure then chosen. new methodology avoids metastable solutions allows different treatment mean-field interactions within phases. These changes are crucial...

Electric field effects on water interfacial properties abound, ranging from electrochemical cells to nanofluidic devices membrane ion channels. On the nanoscale, spontaneous orientational polarization of couples with alignment, resulting in an asymmetric wetting behavior opposing surfaces—a field-induced analogue a chemically generated Janus interface. Using atomistic simulations, we uncover new and significant polarity (sign) dependence dipolar-orientation dynamics hydration layer. Applying...

The quantum cluster equilibrium method is applied to model binary systems of molecular solvents. We minimize the computational effort as well experimental input and present results obtained for completely miscible acetonitrile/acetone, benzene/acetone, water/acetone systems, hardly water/benzene system. Only clusters sizes up n = 3 are these optimized employing low-cost functional PBEh-3c. thermodynamic functions pure liquids in reasonable agreement with experiments. For both non-water...

Human skin oils are significant scavengers of atmospheric oxidants in occupied indoor environments, and squalene is a major ozone-active constituent. Here, we present combined spectroscopic atomistic modeling approach to elucidate the conformational orientational preferences at air/oil interface their implications for reactions with ozone. We find that chains have tendency align surface normal, resulting different concentrations various types its double bonds thus reactivities. also observe...

The well-established quantum cluster equilibrium (QCE) model provides a statistical thermodynamic framework to apply high-level ab initio calculations of finite structures macroscopic liquid phases using the partition function. So far, harmonic approximation has been applied throughout calculations. In this article, we an important correction in evaluation one-particle function and account for anharmonicity. Therefore, implemented analytical Morse derivatives its logarithm with respect...

The established quantum cluster equilibrium approach is further developed in this work. equations are reformulated to result a one-parameter expression, i.e., with one of two empirical parameters eliminated. Instead parametrized constant mean field interaction we present approaches using temperature dependent functions. suggested functions assessed by means test systems, namely hydrogen fluoride and water which investigated concerning their liquid phase properties as well the phenomenon...