The hydrations of Na+ and K+ were investigated by means Monte Carlo simulations with refined ab initio based potentials. These interaction potentials include intramolecular relaxation, polarizability many-body nonadditive effects. Care was taken to ensure proper convergence the MC runs that statistical samples large enough. As a result, agreement attained all experimental data available for hydration ions. water molecules in first shell found have same geometries dipole moments as those...

In this work we present a new proposal to model intermolecular interactions and use it for water molecules. The parameters of the were fitted reproduce single molecule’s electrostatic properties, sample 352 points in refined ab initio molecule deformation potential energy surface (PES), theoretical limit dimerization energy, −20.8 kJ/mol. was able 180 additional PES, 736 pair-interaction computed at MP2/aug-cc-pVQZ′ level with counterpoise correction. Though reproduced diagonal...

The solubility of NaCl, an equilibrium between a saturated solution ions and solid with crystalline structure, was obtained from molecular dynamics simulations using the SPC/E TIP4P-Ew water models. Four initial setups on supersaturated systems were tested sodium chloride (NaCl) solutions to determine conditions computational performance: (1) ionic confined two crystal plates periodic (2) all initially distributed randomly, (3) nanocrystal immersed in pure water, (4) solution. In some cases,...

Aqueous solutions of a light (Nd3+), middle (Gd3+), and heavy (Yb3+) lanthanide ion were studied using ab initio based flexible polarizable analytical potentials in classical molecular dynamics simulations to describe their thermodynamic, structural, dynamic features. To avoid the spurious demise O−H bonds, it was necessary reparametrize an existing water model, which resulted improved description pure water. The good agreement results from with experimental hydration enthalpies,...

A four-site rigid water model is presented, whose parameters are fitted to reproduce the experimental static dielectric constant at 298 K, maximum density of liquid and equation state low pressures. The has a positive charge on each three atomic nuclei negative located bisector HOH bending angle. This distribution allows increasing molecular dipole moment relative models with only charges improves different temperatures. Several other properties ice Ih resulting from numerical simulations in...

Molecular dynamics simulations in the equilibrium isobaric—isothermal (NPT) ensemble were used to examine strength of an external electric field required dissociate methane hydrate sI structure. The water molecules modeled using four-site TIP4P/Ice analytical potential and was described as a simple Lennard-Jones interaction site. A series performed at T = 260 K with P 80 bars 285 400 applied ranging from 1.0 V nm−1 5.0 nm−1. For both (T,P) conditions, applying greater than 1.5 resulted...

Using a simple model it is shown that the cost of constraining hydrated potassium ion inside narrow nanopore smaller than sodium ion. The former allows for greater distortion its hydration shell and can therefore maintain better coordination. We propose in this way larger go through pores more easily. This relevant to molecular basis selective nanopores since mechanism does not depend on details pore, could also operate all sorts nanotubes, from biological synthetic.

The method of flexible constraints was implemented in a Monte Carlo code to perform numerical simulations liquid water and ice Ih the constant number molecules, volume, temperature pressure, instead volume ensembles, using polarizable mobile charge densities harmonic oscillators (MCDHO) model. structural energetic results for at T=298 K rho=997 kg m(-3) were good agreement with those obtained from molecular dynamics. density P=1 atm constraints, rho=1008 m(-3), slightly lower than classical...

We present an analytical potential for intermolecular interactions which includes nonaddivity. fitted this form to ab initio energy surface the water–water interaction and looked into fidelity of fitting two-body interactions, as well three-body four-body nonadditives. tested in a Monte Carlo simulation liquid water. The results obtained led us conclude that model performs very well, giving best reported fit radial distribution functions, enthalpy per water molecule, other parameters....

The addition of water to samarium(II) has been demonstrated have a significant impact on the reduction organic substrates, with majority research dedicated most widely used reagent, samarium diiodide (SmI2). work presented herein focuses reducing capabilities dibromide (SmBr2) and demonstrates how modest change in halide ligand results observable mechanistic differences between SmBr2–water SmI2–water systems that considerable implications terms reactivity two reagents. Quantum chemical from...

A strategy to build interaction potentials for describing ionic hydration of highly charged monoatomic cations by computer simulations, including the polarizable character solvent, is proposed. The method based on hydrated ion concept that has been previously tested case Cr3+ aqueous solutions [J. Phys. Chem. 100, 11748 (1996)]. In present work, potential [Cr(H2O6)]3+ with water adapted a model accounts solvent means mobile charge harmonic oscillator representation (MCHO model) 93, 6448...

This work presents the development of first-principles bromide ion–water interaction potentials using mobile charge density in harmonic oscillators-type model. model allows for a flexible and polarizable character interacting molecules has already been parametrized water–water interactions. The prospected potential energy surfaces ion-water system were computed quantum-mechanically at Hartree–Fock Møller–Plesset second-order perturbation levels. In addition to ion–solvent molecule pair,...

Coordination-induced desolvation or ligand displacement by cosolvents and additives is a key feature responsible for the reactivity of Sm(II)-based reagent systems. High-affinity proton donor such as water glycols also demonstrate coordination-induced bond weakening O-H bond, facilitating reduction broad range substrates. In present work, coordination ammonia to SmI2 was examined using Born-Oppenheimer molecular dynamics simulations mechanistic studies, SmI2-ammonia system compared...

The hydration features of [Mg(H2O)n]2+ and [Ca(H2O)n]2+ clusters with n = 3-6, 8, 18, 27 were studied by means Born-Oppenheimer molecular dynamics simulations at the B3LYP/6-31+G** level theory. For both ions, it is energetically more favorable to have all water molecules in first shell when ≤ 6, but stable lower coordination average structures one molecule not directly interacting ion found for Mg2+ room temperature, showing signatures proton transfer events smaller cation larger one. A...

In this work, we present a new four-site potential for methanol, MeOH-4P, fitted to reproduce the dielectric constant ε, surface tension γ s, and liquid density ρ of pure at T = 298.15 K p 1 bar. The partial charges on each site were taken from OPLS/2016 model with only difference putting negative charge fourth ( M) instead O atom, as done in water models. original Lennard-Jones (LJ) parameters methyl moiety (Me) modified fitting whereas TIP4P-FB used atom without change. Taking into account...

Using both computational and experimental data the SmI₂–MeOH system is directly compared to SmI₂–H₂O uncover basis for their drastic differences in reactivity.

In classical molecular simulations chemical bonds and bond angles have been modeled either as rigid constraints, or nearly harmonic oscillators. However, neither model is a good description of bond, which quantum oscillator that in most cases occupies the ground state only. A can be represented more faithfully by flexible constraint. This means constraint length adapts itself, time, to environment, such rotational potential forces on cancel out. An accurate algorithm for constraints...

Monte Carlo simulations of liquid methanol were performed using a refined ab initio derived potential which includes polarizability, nonadditivity, and intramolecular relaxation. The results present good agreement between the energetic structural properties predicted by model those calculations clusters experimental values gas condensed phases. molecular level picture shows existence both rings linear polymers in phase.

In the present work, we used molecular dynamic simulations of equilibrium NPT ensemble to examine effect an external electric field on three-phase coexistence temperature methane gas, liquid water and hydrate. For these simulations, TIP4P/Ice rigid model a single-site for methane. The were implemented at two pressures, 400 250 bar, over temperatures ranging from 285 320 K 280 315 K, respectively. application in range 0.1–0.9 caused thermal vibrations molecules become attenuated. This...

In this work, a theoretical investigation was made to assess the coordination properties of Pb(ii) in [Pb(H2O)n]2+ clusters, with n = 4, 6, 8, 12, and 29, as well study proton transfer events, by means Born-Oppenheimer molecular dynamics simulations at B3LYP/aug-cc-pVDZ-pp/6-311G level theory, that were calibrated comparison B3LYP/aug-cc-pVDZ-PP/aug-cc-pVDZ calculations. Hemidirected configurations found all cases; radial distribution functions (RDFs) produced defined first hydration shells...

Water addition to Sm(II) has been shown increase reactivity for both SmI2 and SmBr2. Previous work in our groups demonstrated that this can be attributed coordination induced bond weakening enabling substrate reduction through proton-coupled electron transfer. The present examines the interaction of water with samarium dichloride (SmCl2) illustrates importance Sm–X distance upon critical reagent system. Born–Oppenheimer molecular dynamics simulations identify substantial variations among...