There is accumulating evidence that many chemical reactions are accelerated by several orders of magnitude in micrometer-sized aqueous or organic liquid droplets compared to their corresponding bulk phase. However, the molecular origin enhanced rates remains unclear as case spontaneous appearance 1 μM hydrogen peroxide water microdroplets. In this Letter, we consider range ionization energies and whether interfacial electric fields a microdroplet can feasibly overcome high energy step from...

The structure of hydrogen bonded networks is intimately intertwined with their dynamics. Despite the incredibly wide range bond strengths encountered in water clusters, ion-water and liquid water, we demonstrate that previously reported correlation between change equilibrium length OH covalent corresponding shift its harmonic frequency clusters much more broadly applicable. Surprisingly, this describes ratios for both length/harmonic vibrationally averaged length/anharmonic hydronium halide...

We report a database consisting of the putative minima and ∼3.2 × 106 local lying within 5 kcal/mol from for water clusters sizes n = 3-25 using an improved version Monte Carlo temperature basin paving (MCTBP) global optimization procedure in conjunction with ab initio based, flexible, polarizable Thole-Type Model (TTM2.1-F, 2.1) interaction potential water. Several low-lying structures, as well penta-coordinated networks obtained TTM2.1-F potential, were further refined at Møller-Plesset...

We revisit the many-body expansion (MBE) for water-water interactions by examining effects of basis set, including those resulting from set superposition error (BSSE) correction, and electron correlation on various terms selected sizes water clusters up to n = 21. The analysis is performed at second-order Møller-Plesset (MP2) perturbation theory with family augmented consistent sets five zeta quality (aug-cc-pVxZ, x D, T, Q, 5) (H2O)n, 7, 10, 13, 16, 21, which we report either complete MBE...

We present a detailed study of the many-body expansion (MBE) for alkali metal and halide ion–water interactions quantify effect these ions on strength surrounding aqueous hydrogen bonding environment. Building our previous work neutral water clusters [J. P. Heindel S. Xantheas, J. Chem. Theor. Comput. 16 (11), 6843–6855 (2020)], we carry out MBE clusters, Z+/–(H2O)9, where Z = Li+, Na+, K+, Rb+, Cs+, F–, Cl–, Br–, I– compare them with results pure cluster same number "bodies", viz., (H2O)10....

We rely on a total of 23 (cluster size, 8 structural, and 14 connectivity) descriptors to investigate structural patterns connectivity motifs associated with water cluster aggregation. In addition the size n (number molecules), can be further categorized into (i) one-body (intramolecular): covalent OH bond length (rOH) HOH angle (θHOH), (ii) two-body: OO distance (rOO), OHO (θOHO), HOOX dihedral (ϕHOOX), where X lies bisector angle, (iii) three-body: OOO (θOOO), (iv) many-body: modified...

We report extensive benchmark CCSD(T) Complete Basis Set (CBS) estimates of the binding energies, structures, and harmonic frequencies H3O+(H2O) n clusters, = 0-5, including all currently known low-lying energy isomers. These are used to test a previously reported many-body (up 3-body interactions) CCSD(T)-based potential surface (PES) for hydrated proton. A new 4-body term hydronium-water-water-water interactions is introduced. This aimed at refining relative energies isomers n, 4, 5...

We report a Many Body Energy (MBE) analysis of aqueous ionic clusters containing kosmotropic and chaotropic anions cations at the two opposite ends Hofmeister series to quantify how these ions alter interaction between water molecules in their immediate surroundings.

This work constructs an advanced force field, the Completely Multipolar Model (CMM), to quantitatively reproduce each term of energy decomposition analysis (EDA) for aqueous solvated alkali metal cations and halide anions their ion pairings. We find that all individual EDA terms remain well-approximated in CMM ion–water ion–ion interactions, except polarization, which shows errors due partial covalency interactions near equilibrium. quantify onset dative bonding regime by examining change...

Mesoscale water-hydrophobic interfaces are of fundamental importance in multiple disciplines, but their molecular properties have remained elusive for decades due to experimental complications and alternate theoretical explanations. Surface-specific spectroscopies, such as vibrational sum-frequency techniques, suffer from either sample preparation issues or the need complex spectral corrections. Here, we report on a robust "in solution" interface-selective Raman spectroscopy approach using...

We introduce a general framework for many-body force fields, the Completely Multipolar Model (CMM), that utilizes multipolar electrical moments modulated by exponential decay of electron density as common functional form all terms an energy decomposition analysis intermolecular interactions. With this form, CMM model establishes well-formulated damped tensors reach correct asymptotes at both long- and short-range while formally ensuring no catastrophes. describes separable EDA dispersion,...

We describe a method for the post-hoc interpretation of neural network (NN) trained on global and local minima neutral water clusters. use structures recently reported in newly published database containing over 5 × 106 unique cluster networks (H2O)N size N = 3–30. The structural properties were first characterized using chemical descriptors derived from graph theory, identifying important trends topology, connectivity, polygon structure associated with various minima. code to generate...

We present benchmark binding energies of naturally occurring gas molecules CH4, CO2, and H2S in the small cage, namely, pentagonal dodecahedron (512) (H2O)20, which is one constituent cages 3 major lattices (structures I, II, H) clathrate hydrates. These weak interactions require higher levels electron correlation converge slowly with an increasing basis set to complete (CBS) limit, necessitating use large sets up aug-cc-pV5Z subsequent correction for superposition error (BSSE). For host...

The rates of many chemical reactions are accelerated when carried out in micron-sized droplets, but the molecular origin rate acceleration remains unclear. One example is condensation reaction 1,2-diaminobenzene with formic acid to yield benzimidazole. observed enhancements have been rationalized by invoking enhanced acidity at surface methanol solvent droplets low water content enable protonation generate a cationic species (protonated or PFA) formed attachment proton neutral acid. Because...

The Raman spectrum of liquid water is quite complex, reflecting its strong sensitivity to the local environment individual waters. OH-stretch region spectrum, which captures influence hydrogen bonding, has only just begun be unraveled. Here we develop a model for predicting spectra by considering how electric fields distort energy surface each monomer. We find that our capable reproducing bimodal nature main peak, with shoulder at 3250 cm–1 resulting almost entirely from Fermi resonance....

Significance Water’s vibrational spectrum is dynamic: The OH oscillator frequency changes spontaneously within a diffuse envelope on an ultrafast timescale. Here, we explore the mechanics that drive this “spectral diffusion” at molecular level by following time-dependent of single oscillators, each embedded in cage 20 deuterated water molecules, as function temperature. These cages are isolated gas phase and incorporate single, isotopically labeled group can occupy many spectroscopically...

The isomerization pathway between the energetically low-lying Zundel and Eigen isomers of protonated water hexamer was investigated using high-level ab initio calculations including a treatment zero-point corrections. On basis these calculations, Zundel-Eigen found to proceed through stable intermediate isomer, which consists four-membered ring with two single acceptor molecules. inclusion vibrational energy is shown be important for accurately establishing relative energies three relevant...

We present a protocol for classical and nuclear quantum dynamics, in which the energies forces are generated by many-body expansion (MBE), apply it to water clusters using TTM2.1-F MB-Pol interaction potentials at various temperatures. carry out MBE-molecular dynamics (MD) dynamical simulations, of full system approximated two-, three-, four-body terms MBE, compare average potential vibrational density states with simulation, i.e., one no MBE is used. Our results indicate that thermally...

We provide a detailed study of hydrogen bonding arrangements, relative stability, residual entropy, and an analysis the many-body effects in (H2O)20 (D-cage), (H2O)24 (T-cage), (H2O)28 (H-cage) hollow cages making up structures I (sI) II (sII) clathrate hydrate lattices. Based on enumeration possible networks for fixed oxygen atom scaffold, entropy (S0) these three gas phase was estimated at 0.754 82, 44, 17 · Nkb, where N is number molecules kb Boltzmann's constant. A previously identified...

Water is often the testing ground for new, advanced force fields. While functional forms intermolecular interactions have been integral to development of accurate water models, less attention has paid a transferable model intramolecular valence terms. In this work, we present one-body energy and dipole moment surface model, named 1B-UCB, that simple yet can be feasibly adapted both standard potentials. 1B-UCB comparable in accuracy those with much more complex forms, despite having...

We use local diffusion maps to assess the quality of two types collective variables (CVs) for a recently published hydrogen combustion benchmark dataset1 that contains ab initio molecular dynamics (MD) trajectories and normal modes along minimum energy paths. This approach was advocated in2 assessing CVs analyzing reactions modeled by classical MD simulations. report effectiveness this systems quantum MD. In addition CVs, we also global perform committor analysis as proposed in.2 show...