Peter J. Rossky's research while affiliated with Rice University and other places

Publications (287)

Article
Semiconducting nanocrystals passivated with organic ligands have emerged as a powerful platform for light harvesting, light-driven chemical reactions, and sensing. Due to their complexity and size, little structural information is available from experiments, making these systems challenging to model computationally. Here, we develop a machine-learn...
Article
The morphology of semiconducting polymer thin films is known to have a profound effect on their opto-electronic properties. Although considerable efforts have been made to control and understand the processes which influence the structures of these systems, it remains largely unclear what physical factors determine the arrangement of polymer chains...
Article
Understanding molecular transport in polyelectrolyte brushes (PEBs) is crucial for applications such as separations, drug delivery, anti-fouling, and biosensors, where structural features of the polymer control intermolecular interactions. The complex structure and local heterogeneity of PEBs, while theoretically predicted, are not easily accessed...
Article
Full-text available
Solvated electrons are powerful reducing agents capable of driving some of the most energetically expensive reduction reactions. Their generation under mild and sustainable conditions remains challenging though. Using near-ultraviolet irradiation under low-intensity one-photon conditions coupled with electrochemical and optical detection, we show t...
Article
Semiconductor nanocrystals (NCs) interfaced with molecular ligands that function as charge and energy acceptors are an emerging platform for the design of light-harvesting, photon-upconverting, and photocatalytic materials. However, NC systems explored for these applications often feature high concentrations of bound acceptor ligands, which can lea...
Article
Coarse-grained modeling of conjugated polymers has become an increasingly popular route to investigate the physics of organic optoelectronic materials. While ultraviolet (UV)-vis spectroscopy remains one of the key experimental methods for the interrogation of these materials, a rigorous bridge between simulated coarse-grained structures and spectr...
Preprint
Full-text available
Coarse-grained simulations of conjugated polymers have become a popular way of investigating the device physics of organic photovoltaics. While UV-Vis spectroscopy remains one of key experimental methods for the interrogation of these devices, a rigorous bridge between coarse-grained simulations and spectroscopy has never been established. Here we...
Preprint
Graphene is an attractive material for microelectronics applications, given such favourable electrical characteristics as high mobility, high operating frequency, and good stability. If graphene is to be implemented in electronic devices on a mass scale, then it must be compatible with existing semiconductor industry fabrication processes. Unfortun...
Article
We present a path-integral-molecular-dynamics study of the thermodynamic stabilities of DOH⋯ X⁻ and HOD⋯ X⁻ (X = F, Cl, Br, I) coordination in aqueous solutions at ambient conditions. In agreement with experimental evidence, our results for the F⁻ case reveal a clear stabilization of the latter motif, whereas, in the rest of the halogen series, the...
Article
By combining path-integrals molecular dynamics simulations with the accurate MB-pol potential energy surface, we investigate the role of alternative potential models on isotopic fractionation ratios between H and D atoms at dangling positions in water clusters at low temperatures. Our results show clear stabilizations of the lighter isotope at dang...
Article
Significance Conjugated polymers are promising materials for flexible electronics and photovoltaics. Recent progress in polymer design led to a rise in device efficiency. Tailoring intramolecular interactions is a central design element, which allows fine-tuning of optical and electronic properties. However, prediction and measurement of intrinsic...
Article
The rational design of genetically encoded fluorescent bio-sensors, which can detect rearrangements of target proteins via interdomain allostery, is hindered by the absence of mechanistic understanding of the underlying photo-physics. Here, we focus on the modulation of fluorescence by mechanical perturbation in a popular biological probe: enhanced...
Article
An ongoing controversy about water cluster anions concerns the electron-binding motif, whether the charge center is localized at the surface or within the cluster interior. Here, mixed quantum-classical dynamics simulations have been carried out for a wide range of cluster sizes (n ≤ 1000) for [(H2O)n](-) and [(D2O)n](-), based on a non-equilibrium...
Article
Full-text available
Significance Conjugated polymers (CPs) are some of the most attractive organic semiconductors for flexible optoelectronic device applications. The structural and optoelectronic properties of CPs are dependent on both the conformation of individual polymer chains and interactions between chains. Chemists have sought to control these interactions by...
Article
The optoelectronic properties of amorphous conjugated polymers are sensitive to conformational disorder and spectroscopy provides the means for structural characterization of the fragments of the chain which interact with light - "chromophores". A faithful interpretation of spectroscopic conformational signatures, however, presents a key challenge....
Conference Paper
Effect of Polar Vapor Molecules on the Electrical Characteristics of Monolayer Graphene Field-Effect transistors
Article
It is well known that the transport properties of monolayer graphene are degraded by charged impurities present between graphene and either a given substrate or air. Such impurities cause charge scattering of holes and electrons in graphene. In previous work, our group has used both fluoropolymer thin films and polar vapor molecules to dramatically...
Article
We present results of ring polymer molecular dynamics simulations that shed light on the effects of nuclear quantum fluctuations on tunneling motions in cyclic [H2O]3 and [D2O]3, at the representative temperature of T = 75 K. In particular, we focus attention on free energies associated with two key isomerization processes: The first one correspond...
Article
Full-text available
Conjugated polymers in the solid state usually exhibit low fluorescence quantum yields, which limit their applications in many areas such as light-emitting diodes. Despite considerable research efforts, the underlying mechanism still remains controversial and elusive. Here, the nature and properties of excited states in the archetypal polythiophene...
Conference Paper
Recent developments in monolayer graphene production allow its use as the active layer in field-effect transistor technology. Favorable electrical characteristics of monolayer graphene include high mobility, operating frequency, and good stability. These characteristics are governed by such key transport physical phenomena as electron-hole transpor...
Article
Full-text available
The characterization of triplet excited states is essential for research on organic photovoltaics and singlet fission. We report resonance Raman spectra of two triplet oligothiophenes with n-alkyl substituents, a tetramer and hexamer. The spectra of the triplets are more complex than the ground state, and we find that density functional theory calc...
Article
We present results from ring-polymer-molecular-dynamics experiments that provide microscopic insights into the characteristics of the isotopic stabilizations of H and D aqueous species in the first solvation shell of a halide I^-, in water nanoclusters at low temperatures. The analysis of the simplest I^-\cdot(HOD) dimer shows a clear propensity fo...
Article
We develop two classes of quasi-classical dynamics that are shown to conserve the initial quantum ensemble when used in combination with the Feynman-Kleinert approximation of the density operator. These dynamics are used to improve the Feynman-Kleinert implementation of the classical Wigner approximation for the evaluation of quantum time correlati...
Article
We apply the Feynman-Kleinert Quasi-Classical Wigner (FK-QCW) method developed in our previous work [Smith et al., J. Chem. Phys. 142, 244112 (2015)] for the determination of the dynamic structure factor of liquid para-hydrogen and ortho-deuterium at state points of (T = 20.0 K, n = 21.24 nm(-3)) and (T = 23.0 K, n = 24.61 nm(-3)), respectively. Wh...
Article
Here we report on dramatic and favorable changes to the operating characteristics in monolayer graphene field-effect transistors (FETs) exposed to vapor-phase, polar organic molecules in ambient. These changes include significant reduction of the Dirac voltage, accompanied by both an increase in electron and hole mobility, μ, and a decrease in resi...
Article
Recent experiments have reported that the self-assembly of conjugated polymers mimicking rod-coil-rod triblock copolymers (BCPs) in selective solvents exhibits unique aggregate morphologies. However, the nature of the arrangement of the polymers within the aggregates and the spatial organization of the aggregates remain an unresolved issue. We repo...
Article
Exciton energy migration was studied using single molecule spectroscopy of individual conjugated polymer (CP) chains and aggregates. To probe the effect of interchain morphology on energy migration in CP, tailored interchain morphologies were achieved using solvent vapor annealing to construct polymer aggregates that were then studied with single a...
Article
Using ring polymer molecular dynamics simulations, we examine equilibrium and dynamical characteristics of solid-like, aqueous clusters that combine isotopic mixtures of HDO dilute in H2O, at temperatures intermediate between 50 and 175 K. In particular, we focus attention on the relative thermodynamic stabilities of the two isotopes at dangling hy...
Article
The dynamic structure factor of liquid para-hydrogen and ortho-deuterium in corresponding thermodynamic states (T = 20.0 K, n = 21.24 nm-3) and (T = 23.0 K, n = 24.61 nm-3), respectively, has been computed by both the Feynman-Kleinert linearized path-integral (FK-LPI) and Ring-Polymer Molecular Dynamics (RPMD) methods and compared with Inelastic X...
Article
The spatial arrangement of the side chains of conjugated polymer backbones has critical effects on the morphology and electronic and photophysical properties of the corresponding bulk films. The effect of the side‐chain‐distribution density on the conformation at the isolated single‐polymer‐chain level was investigated with regiorandom (rra‐) poly(...
Conference Paper
Full-text available
We report on the substantial improvement of the electronic characteristics of field-effect transistors (FETs) based on chemical vapor deposition (CVD) graphene, reduced graphene oxide (RGO), and molybdenum disulfide (MoS2) by an interacting capping layer of appropriate amorphous or polycrystalline fluoropolymers. All the key 2-dimensional device pr...
Article
We use ring-polymer-molecular-dynamics (RPMD) techniques and the semi-empirical q-TIP4P/F water model to investigate the relationship between hydrogen bond connectivity and the characteristics of nuclear position fluctuations, including explicit incorporation of quantum effects, for the energetically low lying isomers of the prototype cluster [H2O]...
Article
Ring polymer molecular dynamics experiments have been carried out to examine effects derived from nuclear quantum fluctuations at ambient conditions on equilibrium and non-equilibrium dynamical characteristics of charge solvation by a popular simple, rigid, water model, SPC/E , and for a more recent, and flexible, q-TIP4P/F model, to examine the ge...
Article
Many amino acid residue hydrophobicity scales have been created in an effort to better understand and rapidly characterize water-protein interactions based only on protein structure and sequence. There is surprisingly low consistency in the ranking of residue hydrophobicity between scales, and their ability to provide insightful characterization va...
Article
Full-text available
Simulations employing an explicit atom description of proteins in solvent can be computationally expensive. On the other hand, coarse-grained protein models in implicit solvent miss essential features of the hydrophobic effect, especially its temperature dependence, and have limited ability to capture the kinetics of protein folding. We propose a f...
Article
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The temperature and length scale dependence of solvation properties of spherical hard solvophobic solutes is investigated in the Jagla liquid, a simple liquid that consists of particles interacting via a spherically symmetric potential combining a hard core repulsion and a longer ranged soft core interaction, yet exhibits water-like anomalies. The...
Article
We report on the improvement of the electronic characteristics of mono-layered graphene field-effect transistors (FETs) by an interacting capping layer of a suitable fluoropolymer. Capping of mono-layered graphene FETs with CYTOP® improved the on-off current ratio from 5 to 10 as well as increased the field-effect mobility by as much as a factor of...
Article
Full-text available
Photocurrent generation in organic photovoltaics (OPVs) relies on the dissociation of excitons into free electrons and holes at donor/acceptor heterointerfaces. The low dielectric constant of organic semiconductors leads to strong Coulomb interactions between electron-hole pairs that should in principle oppose the generation of free charges. The ex...
Article
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Thin films of water under nanoscopic confinement are prevalent in natural and manufactured materials. To investigate the equilibrium and dynamic behavior of water in such environments, we perform molecular dynamics simulations of water confined between atomistically detailed hydrophobic plates at T = 298 K for pressures (-0.1) ≤ P ≤ 1.0 GPa and pla...
Article
The hydrated electron is a fascinating species that has captured the scientific attention of chemists for more than 50 years. Although the experimental detection of the hydrated electron dates back only to 1962, the existence of the hydrated electron has been continuously speculated since the experimental observation and postulation of the first so...
Article
We investigate the thermal stability of helical hydrophobic oligomers using a three-dimensional, water-explicit lattice model and the Wang-Landau Monte Carlo method. The degree of oligomer helicity is controlled by the parameter ε(mm) < 0, which mimics monomer-monomer hydrogen bond interactions leading to the formation of helical turns in atomistic...
Article
We investigate the thermodynamics of hydrophobic oligomer collapse using a water-explicit, three-dimensional lattice model. The model captures several aspects of protein thermodynamics, including the emergence of cold- and thermal-unfolding, as well as unfolding at high solvent density (a phenomenon akin to pressure-induced denaturation). We show t...
Article
We investigate the microscopic mechanism of cold and heat denaturation using a 3D lattice model of a hydrated protein in which water is represented explicitly. The water model, which incorporates directional bonding and tetrahedral geometry, captures many aspects of water thermodynamics and properly describes hydrophobic hydration around apolar sol...
Article
The behavior of water confined on nanometer length scales is important in a diverse set of technical and scientific contexts, ranging from the performance of fuel cells and biological molecular machines to the design of self-assembling nanoscale materials. Here, we review recent insights into the structure and thermodynamics of confined water that...
Article
Full-text available
We examine the range of validity of the Gaussian model for various water-like liquids whose intermolecular potentials differ from SPC/E water, to provide insight into the temperature dependence of the hydrophobic effect for small hard sphere solutes. We find that low compressibility liquids that have more close-packed network structures show much l...
Article
Full-text available
Methanol is an amphiphilic solute whose aqueous solutions exhibit distinctive physical properties. The volume change upon mixing, for example, is negative across the entire composition range, indicating strong association. We explore the corresponding behavior of a Jagla solvent, which has been previously shown to exhibit many of the anomalous prop...
Article
The energetics of water proximal to apolar groups is analyzed from a statistical perspective in the realistic context of polypeptide hydration. Analysis of a series of molecular dynamics simulations of a 16-residue polypeptide in water reveals a correlation between hydrogen bond energy and local packing when there is overcoordination of the water m...
Article
The reorientation dynamics of interfacial water molecules was recently shown to change non-monotonically next to surfaces of increasing hydrophilicity, with slower dynamics next to strongly hydrophobic (apolar) and very hydrophilic surfaces, and faster dynamics next to surfaces of intermediate hydrophilicities. Through a combination of molecular dy...
Article
Full-text available
A series of quantum molecular dynamics simulations have been performed to investigate the energetic, structural, dynamic, and spectroscopic properties of methanol cluster anions, [(CH(3)OH)(n)](-), (n = 50-500). Consistent with the inference from photo-electron imaging experiments, we find two main localization modes of the excess electron in equil...
Article
The redox chemistry of supramolecular nanotubes self-assembled from amphiphilic cyanine dye 3,3′-bis(2-sulfopropyl)-5,5′,6,6′-tetrachloro-1,1′-dioctylbenzimidacarbocyanine (C8S3) in aqueous solution was investigated by spectroelectrochemistry. The absorption spectra during the redox-reaction were analyzed by singular value decomposition (SVD) and s...
Chapter
Computer simulation of quantum systems in solution are allowing the direct observation of electronic dynamics of solutes at a molecular level on the same timescale as that probed by ultrafast transient spectroscopy. Here, we describe some of our recent theoretical approaches to the analysis of electronic spectroscopy and relaxation dynamics in solu...
Article
When two macroscopic and repulsive surfaces are immersed in water, evaporation of the confined liquid is favored thermodynamically below a critical separation: the evaporation length scale. We use thermophysical property data to evaluate the evaporation length scale of water, and compare it to that of several common organic liquids over a broad ran...
Article
The computational expense of folding atomistically detailed protein models is prohibitive. Hence minimalist models of proteins are a popular choice. The minimalist models developed so far have excluded water, and treated the hydrophobic effect as an effective attraction between hydrophobic monomers. This simplified treatment does not capture the te...
Article
Full-text available
We measure the solvation free energy, Δμ*, for hard spheres and Lennard-Jones particles in a number of artificial liquids made from modified water models. These liquids have reduced hydrogen bond strengths or altered bond angles. By measuring Δμ* for a number of state points at P = 1 bar and different temperatures, we obtain solvation entropies and...
Article
Paul F. Barbara, 57, passed quietly on Sunday, 31 October 2010, from complications following cardiac arrest. He made deep contributions to understanding how molecular shapes and reactivities are induced by their environments. Paul's intense focus on understanding molecules at their most fundamental level had very early roots. After his election to...
Article
Electrochemistry and electrogenerated chemiluminescence (ECL) of selected substituted BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) dyes have been studied. The location and nature of substituents on positions 1-8 are important in predicting the behavior, and especially the stability, of the radical ions formed on electron transfer. Dyes with...
Article
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We have used a recently developed electron-methanol molecule pseudopotential in approximate quantum mechanical calculations to evaluate and statistically analyze the physical properties of an excess electron in the field of equilibrated neutral methanol clusters ((CH(3)OH)(n), n=50-500). The methanol clusters were generated in classical molecular d...
Article
To augment the experimental search for a nonfluorous capping ligand that is effective in dispersing nanoparticles in supercritical carbon dioxide, we have developed a simulation protocol, involving atomistic molecular dynamic simulations, which semiquantitatively reproduces empirical observations and hence can be used to gain insight into the relev...
Article
There is considerable interest in developing a nonfluorous capping ligand that is effective in dispersing nanoparticles in supercritical carbon dioxide. To augment the experimental search for such a molecule, a simulation protocol is developed, involving atomistic molecular dynamics simulations, which captures the relevant physical phenomena relate...
Article
We have undertaken atomistic molecular simulations to systematically determine the structural contributions to the hydrophobicity of fluorinated solutes and surfaces compared to the corresponding hydrocarbon, yielding a unified explanation for these phenomena. We have transformed a short chain alkane, n-octane, to n-perfluorooctane in stages. The f...
Article
The dynamics of water next to hydrophobic groups is critical for several fundamental biochemical processes such as protein folding and amyloid fiber aggregation. Some biomolecular systems, like melittin or other membrane-associated proteins, exhibit extended hydrophobic surfaces. Due to the strain these surfaces impose on the hydrogen (H)-bond netw...
Article
We present simulations of exciton dissociation and charge separation processes in the prototypical conjugated polymer, poly-p-phenylenevinylene. Our mixed quantum/classical simulations focus on the nonadiabatic excited state dynamics of single and pi-stacked oligomers of varying length. By applying a constant external electric field, our simulation...
Article
In this lecture, aspects of the hydration of hydrophobic interfaces that are emergent nanoscale properties of the interface chemical structure are discussed. General results inferred from systematic computational studies are emphasized, with a central theme focusing on the separate roles of surface topography and surface chemistry. The roles of sur...
Article
We examine the behavior of a bead-on-a-string hard sphere polymer in molecular dynamics simulation in a solvent whose particles interact via the Jagla potential, a spherically symmetric ramp potential with two characteristic lengths: an impenetrable hard core and a penetrable soft core. The Jagla fluid has been recently shown to possess water-like...
Article
We have used mixed quantum classical molecular dynamics simulations to explore the role of structural relaxation when binding an excess electron to neutral water clusters. The structural and spectral properties of the water cluster anions were investigated as a function of the size (n = 45 and 104), nominal temperature (T(nom) = 50, 100, and 150 K)...
Article
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We use atomistic computer simulation to explore the relationship between mesoscopic (liquid drop contact angle) and microscopic (surface atomic polarity) characteristics for water in contact with a model solid surface based on the structure of silica. We vary both the magnitude and direction of the solid surface polarity at the atomic scale and cha...
Article
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A general formalism for introducing nuclear quantum effects in the expression of the quantum time correlation function of an operator in a multilevel electronic system is presented in the adiabatic limit. The final formula includes the nuclear quantum time correlation functions of the operator matrix elements, of the energy gap, and their cross ter...
Article
We present results from the first nonadiabatic (NA), nonequilibrium mixed quantum-classical molecular dynamics simulations of pi-stacked oligophenylvinylene (OPV) chains with a quantum electronic Hamiltonian (Pariser-Parr-Pople with excited states given by configuration interaction) that goes beyond the tight-binding approximation. The chains pack...
Article
We perform molecular dynamics simulations of water confined between atomically detailed hydrophobic, hydrophilic, and heterogeneous (patchy) nanoscale plates. We study the effects of temperature 220 <or= T <or= 300 K on confined water's behavior at various pressures -0.2 <or= P <or= 0.2 GPa and plate separations 0.5 <or= d <or= 1.6 nm. Combining th...
Article
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We present the results of mixed quantum/classical simulations on relaxed thermal nanoscale water cluster anions, (H(2)O)(n)(-), with n=200, 500, 1000, and 8000. By using initial equilibration with constraints, we investigate stable/metastable negatively charged water clusters with both surface-bound and interior-bound excess electron states. Charac...
Article
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We present results from molecular dynamics simulations of water confined by two parallel atomically detailed hydrophobic walls. Simulations are performed at T = 300 K and wall-wall separation d = 0.6-1.6 nm. At 0.7 < or = d < or = 0.9 nm, a first order transition occurs between a bilayer liquid (BL) and a trilayer heterogeneous fluid (THF) as water...
Article
The stability of the native folds of globular proteins is rather remarkable, in that this stability is marginal and restricted to a relatively narrow window of thermodynamic and solution composition conditions (1). The development of a deep understanding of the balance of forces that tip the scales between native and denatured states in terms of th...
Article
The electronic ground and excited-state structures of the betaine dye molecule pyridinium- N-phenoxide [4-(1-pyridinio)phenolate] are investigated both in the gas phase and in aqueous solution, using the reference interaction site model self-consistent-field (RISM-SCF) procedure within a CASSCF framework. We obtain the total free energy profiles in...
Article
Full-text available
Globular proteins undergo structural transitions to denatured states when sufficient thermodynamic state or chemical perturbations are introduced to their native environment. Cold denaturation is a somewhat counterintuitive phenomenon whereby proteins lose their compact folded structure as a result of a temperature drop. The currently accepted expl...
Article
We investigate the properties of a two-dimensional lattice heteropolymer model for a protein in which water is explicitly represented. The model protein distinguishes between hydrophobic and polar monomers through the effect of the hydrophobic monomers on the entropy and enthalpy of the hydrogen bonding of solvation shell water molecules. As experi...
Article
The ground and excited state dynamics of poly(p-phenylenevinylene) (PPV) chains is studied through an implementation of mixed quantum/classical molecular dynamics simulation. The model used in the simulations combines the semiempirical Pariser-Parr-Pople (PPP) Hamiltonian to treat the pi molecular electronic structure with a mechanical force field...
Article
Full-text available
To better understand the role of surface chemical heterogeneity in natural nanoscale hydration, we study via molecular dynamics simulation the structure and thermodynamics of water confined between two protein-like surfaces. Each surface is constructed to have interactions with water corresponding to those of the putative hydrophobic surface of a m...
Article
The Feynman-Kleinert linearized path integral molecular dynamics (FK-LPI), ring polymer molecular dynamics (RPMD), and centroid molecular dynamics (CMD) methods are applied to the simulation of normal liquid helium. Comparisons of the simulation results at the T = 4 K and rho = 0.01873 A-3 state point are presented. The calculated quantum correlati...
Article
We investigate the effect of temperature and pressure on polypeptide conformational stability using a two-dimensional square lattice model in which water is represented explicitly. The model captures many aspects of water thermodynamics, including the existence of density anomalies, and we consider here the simplest representation of a protein: a h...
Article
We examine by molecular dynamics simulation the solubility of small apolar solutes in a solvent whose particles interact via the Jagla potential, a spherically symmetric ramp potential with two characteristic lengths: an impenetrable hard core and a penetrable soft core. The Jagla fluid has been recently shown to possess water-like structural, dyna...
Article
Full-text available
We present a kinetic analysis of the nonadiabatic decay mechanism of an excited state hydrated electron to the ground state. The theoretical treatment is based on a quantized, gap dependent golden rule rate constant formula which describes the nonadiabatic transition rate between two quantum states. The rate formula is expressed in terms of quantum...
Article
We perform molecular dynamics simulations of water in the presence of hydrophobic/hydrophilic walls at T = 300 K and P = 0 GPa. For the hydrophilic walls, we use a hydroxylated silica model introduced in previous simulations [Lee, S. H.; Rossky, P. J. J. Chem. Phys. 1994, 100, 3334. Giovambattista, N.; Rossky, P. J.; Debenedetti, P. G.; Phys. Rev....
Article
Water around biomolecules slows down with respect to pure water, and both rotation and translation exhibit anomalous time dependence in the hydration shell. The origin of such behavior remains elusive. We use molecular dynamics simulations of water dynamics around several designed protein models to establish the connection between the appearance of...
Article
Full-text available
We have performed mixed quantum-classical molecular dynamics simulations of the relaxation of a ground state excess electron at interfaces of different phases of water with air. The investigated systems included ambient water/air, supercooled water/air, Ih ice/air, and amorphous solid water/air interfaces. The present work explores the possible con...
Article
The Feynman-Kleinert linearized path-integral [J. A. Poulsen et al., J. Chem. Phys. 119, 12179 (2003)] representation of quantum correlation functions is applied to compute the spectrum of density fluctuations for liquid neon at $T=27.6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, $p=1.4\phantom{\rule{0.3em}{0ex}}\text{bar}$, and $Q$ vector $1.55\phantom...
Article
We perform molecular dynamics simulations of water confined between nanoscale surfaces (≈3.2 × 3.2 nm2) with various patterns of hydrophobicity and hydrophilicity at T = 300 K, −0.05 GPa ≤ P ≤ 0.2 GPa, and plate separations 0.5 nm ≤ d ≤ 1.6 nm. We find that the water surface density in the first hydration layer is considerably higher at a hydrophob...
Article
Mixed quantum-classical atomistic simulations have been carried out to investigate the mechanistic details of excited state intramolecular electron transfer in a betaine-30 molecule in acetonitrile. The key electronic degrees of freedom of the solute molecule are treated quantum mechanically using the semiempirical Pariser-Parr-Pople Hamiltonian, i...
Article
The Feynman−Kleinert Linearized Path Integral (FK-LPI) representation of quantum correlation functions is extended in applications and algorithms. Diffusion including quantum effects for a flexible simple point charge model of liquid water is explored, including new tests of internal consistency. An ab initio quantum correction factor (QCF) is also...
Article
The previously introduced method of evaluating quantum mechanical time correlation functions using as input only classical simulation data is generalized and applied to two anharmonic model systems, as a further test. The quantum correction approach utilizes the relation between a general quantum correlation function and its classical analog. For t...

Citations

... The study confirmed that hot carrier generation within a plasmonic metal is directly correlated to the volume integration of |E| 2 within the electron mean free path of the metal. The same idea can also be applied to Al@Cu 2 O core-shell nanoparticles for reverse water-gas shift, Al-Pd antenna-reactors for H 2 dissociation and C-F activation, and solvated electrons from Au and Ag nanoparticles [5,[102][103][104]. There are many publications which correlate absorption or extinction crosssections with wavelength-dependent reactivity, especially when the classic absorption cross-section is very close to its extinction cross-section in Au nanoparticles [31,53,58,62]. ...
... Our investigations also unveil the formation of a charge-transfer complex in tryptamine-derived isocyanides induced by aggregation instead of intramolecular charge transfer. [8][9][10][11][12] ...
... [1d,2,4] Furthermore, orthogonal analytical techniques like the UV/Vis have comparative advantages such as (1) providing direct information about the NP's molar concentration and optical activity through its absorbance, (2) indicating the samples' homogeneity via the full-width half maximum FWHM and, (3) high applicability to dynamic processes such as NP synthesis. Thus far, proofof-concept work using extinction spectra and ML is limited to the prediction of size and size distribution of purified and homogeneous Au nanospheres (NSs) and nanowires (NWs), with error rates of < 10 %. [5] These purified NPs have simple morphologies exhibiting only one or two LSPR modes. Critically, they do not reflect the actual conditions of inherent shape anisotropies found in as-synthesized NP mixtures. ...
... As an irreplaceable analysis means, ion chromatography (IC) has become indispensable for the separation and detection of various ionizable chemicals (anionic compounds especially) in scientific research, industry area, and quality administration [1][2][3]. As the principal role in IC separation, the stationary phase attracted increasing attentions in last decades [4]. ...
... The work in [22] further applied kernel support vector machines (kernel SVMs) to deal with non-linear relationships between polymer sequences and their properties, achieving great predictive performance. For deep learning examples, the work in [35] predicted mechanical properties of polymer-carbon nanotube surfaces using convolutional neural networks (CNNs) while recurrent neural networks (RNNs) were also used in [40,51] to learn the latent relationships between polymer sequences and their properties. However, all these prediction methods are significantly limited by the scarcity of high-quality polymer property data. ...
... This conformation can be transferred to the solid state, and can in turn subtly change the electronic properties in the bulk. [11,12] For several (co-)polymers a planarising effect of alkyl side chains on the backbone has been reported, with the effect depending on the position of the alkyl groups. [13][14][15][16][17] In particular, long side chains were suggested to enhance planarity and thus packing in films. ...
... 66,67 As discussed in detail in the original studies, both TTM-nrg 55,56 and MB-nrg 57,58 PEFs are derived from Eq. (1) and use the MBpol PEF for representing water-water interactions. 52-54 MB-pol has been shown by us and others to correctly reproduce the properties of water, 66,68 from small clusters in the gas phase [69][70][71][72][73][74][75][76][77][78][79][80] to liquid water, 81-87 the air/water interface, [88][89][90][91][92] and ice. [93][94][95][96] In the TTM-nrg PEFs, all ion-water many-body contributions, i.e., ε 2B to ε NB , are described by an implicit NB term represented by classical polarization. ...
... The analysis of structural determinants of high FQY for designing the improved FP involves diverse methodological arsenal [5,12]. Its tools are molecular modeling [13][14][15][16], structural analysis [8,[17][18][19], directed evolution of proteins [20,21] and the studies of isolated chromophores [9,[22][23][24]. The combination of the above approaches proves to be especially effective, in some cases allowing the building of generalized models of function of a particular type of chromophore [9,10,25]. ...
... Path integral molecular dynamics (PIMD) simulations allow NQEs to be exactly included in the calculation of static equilibrium properties, such as QKEs and fractionation ratios, on a given potential energy surface. [35][36][37] Recent studies have combined path integral simulations and empirical fixed charge force fields to assess how NQEs affect the hydrogen bond and water exchange dynamics around monatomic alkali and halide ions, 38,39 the kinetic energy changes they engender in the water molecules around them, 39,40 and the effect of these changes on the fractionation ratios and infrared absorption spectra of the aqueous solutions. 40 In this work, we perform ab initio path integral molecular dynamics (AI-PIMD) simulations, which provide a quantum mechanical description of both the electrons and nuclei, of liquid water and aqueous solutions containing the monatomic Na + and Cl − ions and the polyatomic HPO 2− 4 ion. ...
... In 1990, Coe et al. (4) studied vertical electron binding energies (VBEs; the peak energy of eBE distribution) of water cluster anions generated in molecular beams and predicted the VBE of e aq − in bulk water to be 3.3 eV. However, it is still debated whether an excess electron is internally bound or trapped on the surface of these clusters (5)(6)(7). If the latter, the VBE predicted using clusters must be incorrect. ...