The role that van der Waals (vdW) attractive forces play in the hydration and association of atomic hydrophobic solutes such as argon (Ar) in water is reanalyzed using the local molecular field (LMF) theory of those interactions. In this problem, solute vdW attractive forces can reduce or mask hydrophobic interactions as measured by contact peak heights of the ArAr correlation function compared to reference results for purely repulsive core solutes. Nevertheless, both systems exhibit a characteristic hydrophobic inverse temperature behavior in which hydrophobic association becomes stronger with increasing temperature through a moderate temperature range. The new theoretical approximation obtained heremore »
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In this paper, electrochemical doublelayer capacitances of charged carbon nanotube (CNT) forests with tetraethyl ammonium tetrafluoro borate electrolyte in propylene carbonate are studied on the basis of molecular dynamics simulation. Direct molecular simulation of the filling of pore spaces of the forest is feasible even with realistic, small CNT spacings. The numerical solution of the Poisson equation based on the extracted average charge densities then yields a regular experimental dependence on the width of the pore spaces, in contrast to the anomalous pattern observed in experiments on other carbon materials and also in simulations on planar slotlike pores. The capacitancesmore »

Laying a basis for molecularly specific theory for the mobilities of ions in solutions of practical interest, we report a broad survey of velocity autocorrelation functions (VACFs) of Li ^{+} and PF _{6} ^{} ions in water, ethylene carbonate, propylene carbonate, and acetonitrile solutions. We extract the memory function, γ(t), which characterizes the random forces governing the mobilities of ions. Here, we provide comparisons controlling for the effects of electrolyte concentration and ionpairing, van der Waals attractive interactions, and solvent molecular characteristics. For the heavier ion (PF _{6} ^{}), velocity relaxations are all similar: negative tail relaxations for the VACFmore »

Extensive allatom molecular dynamics calculations on the water–squalane interface for nine different loadings with sorbitan monooleate (SPAN80), at T = 300 K, are analyzed for the surface tension equation of state, desorption freeenergy profiles as they depend on loading, and to evaluate escape times for adsorbed SPAN80 into the bulk phases. These results suggest that loading only weakly affects accommodation of a SPAN80 molecule by this squalane–water interface. Specifically, the surface tension equation of state is simple through the range of high tension to high loading studied, and the desorption freeenergy profiles are weakly dependent on loading here. The perpendicularmore »Cited by 1

We use ab initio molecular dynamics (AIMD) calculations and quasichemical theory (QCT) to study the innershell structure of F(aq) and to evaluate that singleion free energy under standard conditions. Following the “no split occupancies” rule, QCT calculations yield a free energy value of 101 kcal/mol under these conditions, in encouraging agreement with tabulated values (111 kcal/mol). The AIMD calculations served only to guide the definition of an effective innershell constraint. QCT naturally includes quantum mechanical effects that can be concerning in more primitive calculations, including electronic polarizability and induction, electron density transfer, electron correlation, molecular/atomic cooperative interactions generally, molecular flexibility,more »Cited by 2Full Text Available
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