We present the Voronoi Deformation Density (VDD) method for computing atomic charges. The VDD does not explicitly use basis functions but calculates amount of electronic density that flows to or from a certain atom due bond formation by spatial integration deformation over cell. compare our well-known Mulliken, Hirshfeld, Bader, and Weinhold [Natural Population Analysis (NPA)] charges variety biological, organic, inorganic molecules. Mulliken are (again) shown be useless heavy set...

We report the first computational study of a fully atomistic model ruthenium-catalyzed transfer hydrogenation formaldehyde and reverse reaction in an explicit methanol solution. Using ab initio molecular dynamics techniques, we determined thermodynamics, mechanism, electronic structure along path. To assess effect solvent quantitatively, make direct comparison with gas-phase reaction. find that energy profile solution bears little resemblance to gas phase distinct solvation barrier is found:...

The enantioselective outcome of transfer hydrogenation reactions that are catalysed by ruthenium(II) amino alcohol complexes was studied means a systematically varied series ligands. It found both the substituent at 1-position in 2-amino-1-alcohol ligand and amine functionality influence enantioselectivity reaction to large extent: enantioselectivities (ee values) up 95% were obtained for reduction acetophenone. catalytic cycle examined density functional theory level. formation hydrogen...

We discuss the application of Helfrich's surface torque density concept to microemulsion design and analysis from three different angles: (i) point view coarse-grained molecular simulations, using Dissipative Particle Dynamics, including charge interactions added salt, (ii) an approximate double-film model for surface, (iii) comparison with formulation approaches. The simulations use that can be calculated unambiguously stress profile, provided is tensionless. Very good agreement found on...

We present a density functional theory based computational study comparing simplified models for the ruthenium(II)- and iridium(I)-catalyzed transfer hydrogenation of ketones. For ruthenium compound our results confirm earlier findings that involves hydride occurs via concerted hydrogen mechanism with no direct ruthenium−ketone binding along reaction path. In contrast, iridium calculations suggest proceeds between simultaneously coordinated ketone alcohol. find both metal complexes formation...

We present a density-functional theory based molecular dynamics study of the structural, dynamical, and electronic properties liquid methanol under ambient conditions. The calculated radial distribution functions involving oxygen hydroxyl hydrogen show pronounced bonding compare well with recent neutron diffraction data. observe that, in line infrared spectroscopic data, hydroxyl-stretching mode is significantly redshifted liquid, whereas bending shows blueshift. A substantial enhancement...

This work presents a multiscale computational approach to probe the behavior of polymer/clay nanocomposites based on poly(ethylene oxide) (PEO)/montmorillonite (MMT) as obtained from water intercalation. In details, our modeling recipe is four sequential steps: (a) atomistic molecular dynamics simulations derive interaction energy values among all system components; (b) mapping these onto mesoscale dissipative particle parameters; (c) mesoscopic determine density distributions and...

A new class of peptide has been created, polypeptide-b-designed peptides, which unites the useful qualities two constituent types. We demonstrate synthesis and self-assembly possibilities this chimera with a series amphiphilic peptides in hydrophobic block is poly(gamma-benzyl l-glutamate) (PBLG) hydrophilic coiled-coil forming (denoted E). The synthetic approach was to synthesize on solid phase, followed by ring-opening polymerization gamma-benzyl l-glutamate N-carboxyanhydride, initiated...

We present an innovative, multiscale computational approach to probe the behaviour of polymer-clay nanocomposites (PCNs). Our modeling recipe is based on 1) quantum/force-field-based atomistic simulation derive interaction energies among all system components; 2) mapping these values onto mesoscopic bead-field (MBF) hybrid-method parameters; 3) simulations determine density distributions and morphologies (i.e., intercalated versus exfoliated); 4) at finite-element levels calculate relative...

Many food emulsions are stabilized by functional egg yolk biomolecules, which act as surfactants at the oil/water interface. Detailed experimental studies on emulsifying properties have been largely hindered due to difficulty in isolating individual chemical species. Therefore, this work presents a molecular model of an interfacial system where emulsifier is one most surface-active proteins from low-density lipoproteins (LDL), so-called Apovitellenin I. Dissipative particle dynamics (DPD)...

Abstract The onset of water gelation around a collagen‐like triple helix peptide was studied at ambient temperature and pressure by performing Molecular Dynamics simulations. radial distribution functions the oxygen hydrogen atoms are distorted below 4 Å from peptide. distortion is accompanied breakdown tetrahedral coordination hydrogen‐bonded network molecules. shell consists alternating regions higher lower density. In agreement with experiments we find that first hydration kinetically...

A series of amphiphilic lipopeptides, ALPs, consisting an alternating hydrophilic and hydrophobic amino acid residue sequence coupled to a phospholipid tail, was designed form supramolecular assemblies composed beta-sheet monolayers decorated by lipid tails at the air-water interface. straightforward synthetic approach based on solid-phase synthesis, followed efficient purification protocol used prepare lipid-peptide conjugates. Structural insight into organization provided surface pressure...

Abstract Surfactant EOR is an attractive method to recover the residual oil left behind in reservoir after water flooding. The formulation of effective surfactant system a relatively complex and often time consuming process because activity depends on crude composition must therefore be tailored oil. In practice many (and solvent) combinations need tested laboratory optimize performance. An alternative approach, which focus this paper, start with molecular structure apply Molecular Modeling...

In the tertiary oil recovery method known as "polymer flooding", viscosity of injected water is increased by dissolving partially hydrolyzed polyacrylamide so to lower mobility ratio and raise vertical areal sweep efficiencies. However, its drawbacks include degradation polymer in reservoir due (1) shear while passing through chokes, perforations, pore throats, (2) morphological changes induced divalent ions, (3) complete hydrolysis at high temperatures. These factors adversely affect flood....

Abstract Three analogs of alamethicin F50/5, labelled with the TOAC (=‘2,2,6,6‐tetramethylpiperidin‐1‐oxyl‐4‐amino‐4‐carboxylic acid’) spin label at positions 1 ( Alm1 ), 8 Alm8 and 16 Alm16 resp., were studied by Electron‐Spin‐Resonance (ESR) Pulsed Electron–Electron Double‐Resonance (PELDOR) techniques in solvents different polarity to investigate self‐assembly amphipathic helical peptides membrane‐mimicking environments. In polar solvents, forms homogeneous solutions. weakly...

Abstract Zervamicin is a voltage‐gated ion‐channel‐forming peptide. Channels are generally considered to be formed by first insertion of amphipathic molecules into the phospholipid bilayer, followed self‐assembly variable number transmembrane helices. We have studied length peptide structure address question whether this long enough span bilayer. The pulsed electron‐electron double resonance (PELDOR) spectroscopic technique was used determine helical molecule in membrane‐mimicking solvents....

This work provides a framework to digitally assess any droplet's static and dynamic contact angles on coatings polymeric substrates. We are introducing new dissipative particle dynamics coarse-grained model attain the spatiotemporal conditions coexistence of different phases that such investigation dictates. Two computational techniques additionally developed; robust technique calculate angle using density profiles perturbation method evaluate angles. A parallel force surface is applied...

Abstract Here we report theoretical studies on the ruthenium‐catalyzed reduction of acetophenone (and 2‐hexanone) with intent understanding relative roles catalyst and substrate along reaction path. Overall ten pathways are examined. The first eight for acetophenone: they arise from presence two catalysts, more enantioselective one labeled 1 , poorer 2 multiplied by configurations that metal center catalysts can assume, approaches, Re ‐ Si ‐side, to catalyst. Two examined hexanone entail...

Abstract Surfactant formulations are extensively being developed in the oil industry for Enhanced Oil Recovery (EOR) applications. Surfactants suitable EOR will form an oil-brine microemulsion (µE) with ultra-low interfacial tension (IFT), necessary high recovery factors. Experimental screening of surfactants, to identify reservoir conditions, is a laborious and time consuming process. In this paper we demonstrate alternative, novel, molecular modeling approach which predicting µE properties...

We present a multiscale modeling protocol to generate realistic amorphous polymer surfaces. Our computational approach consists of several steps having different levels molecular detail. Initially, we course-grained surface that is completely relaxed using mesoscopic simulation methods. In the second step transform equilibrated coarse-grained atomistic detail with special "mapper" takes as input morphology and uses Monte Carlo techniques structure. final atomistically detailed by performing...

Abstract State‐of‐the‐art multiscale computational chemistry simulations is employed to predict diffusivity of small gaseous molecules in a generic polyphenylene ether (PPE). The diffusivities are obtained from trajectory analysis molecular dynamics using coarse‐grained dissipative particle (DPD) design the amorphous starting structure. Required intra‐ and intermolecular parameters DPD automatically generated automated fragmentation parametrization protocol. A comparison calculated diffusion...