Our picture of reactions on electronically excited states has evolved considerably in recent years, due to advances our understanding points degeneracy between different electronic states, termed "conical intersections" (CIs). CIs serve as funnels for population transfer and play a central role ultrafast photochemistry. Because most practical photochemistry occurs solution protein environments, it is important understand the complex environments directing excited-state dynamics generally,...

Functional soft materials, comprising colloidal and molecular building blocks that self-organize into complex structures as a result of their tunable interactions, enable wide array technological applications. Inverse methods provide systematic means for navigating inherently high-dimensional design spaces to create materials with targeted properties. While multiple physically motivated inverse strategies have been successfully implemented in silico, translation guiding experimental...

The C≡N bond is a powerful probe of protein structure and dynamics because it absorbs in region the infrared spectrum apart from other vibrations that occur naturally proteins, its absorption line shape sensitive to specific characteristics local environment. Since polarity experienced by can differ dramatically within protein, spectroscopy site-specifically labeled residue be used infer environment protein. It has been shown experimentally acetonitrile water different terms peak position...

Accurate modeling of the behavior high-explosive (HE) materials requires knowledge equation state (EOS) for both reactant and product states material. Historically, EOS models have been calibrated to reproduce experimental data, but there is growing interest in first-principles predictions HE behavior. The particularly challenging model because wide range density temperature conditions that are relevant as well requirement include chemical reactivity any kind atomistic simulation. Density...

Inverse methods of statistical mechanics have facilitated the discovery pair potentials that stabilize a wide variety targeted lattices at zero temperature. However, such are complicated by need to compare, within optimization framework, energy desired lattice all possibly relevant competing structures, which not generally known in advance. Furthermore, ground-state stability does guarantee target will readily assemble from fluid upon cooling higher Here, we introduce molecular dynamics...

For colloidal semiconductor nanocrystals (NCs), replacement of insulating organic capping ligands with chemically diverse inorganic clusters enables the development functional solids in which adjacent NCs are strongly coupled. Yet controlled assembly methods lacking to direct arrangement charged, cluster-capped into open networks. Herein, we introduce coordination bonds between thus linking highly gel As cations (Pt(2+)) added dilute (under 1 vol %) chalcogenidometallate-capped CdSe NC...

We demonstrate the utility of an unsupervised machine learning tool for detection phase transitions in off-lattice systems. focus on application principal component analysis (PCA) to detect freezing two-dimensional hard-disk and three-dimensional hard-sphere systems as well liquid-gas separation a patchy colloid model. As we demonstrate, PCA autonomously discovers order-parameter-like quantities that report transitions, mitigating need priori construction or identification suitable order...

In this article we describe the unique insights into electronic structure of molecules provided by generalized valence bond (GVB) theory. We consider selected prototypical hydrocarbons as well a number hypervalent and set first- second-row isoelectronic species. The GVB wave function is obtained variationally optimizing orbitals spin coupling in function. generalization Hartree–Fock (HF) function, lifting double occupancy restriction on subset HF associated orthogonality constraints....

Gelation of colloidal nanocrystals (NCs) emerged as a strategy to preserve inherent nanoscale properties in multiscale architectures. Yet available gelation methods still struggle reliably control optical phenomena such photoluminescence and localized surface plasmon resonance (LSPR) across NC systems due processing variability. Here, we report on an alternative method based physical inter-NC interactions: short-range depletion-attractions balanced by long-range electrostatic repulsions. The...

We outline how principal component analysis (PCA) can be applied to particle configuration data detect a variety of phase transitions in off-lattice systems, both and out equilibrium. Specifically, we discuss its application study 1) the nonequilibrium random organization (RandOrg) model that exhibits transition from quiescent steady-state behavior as function density, 2) orientationally positionally driven equilibrium for hard ellipses, 3) compositionally demixing non-additive binary...

Traditionally, hydrodynamics simulations are performed with a single equation-of-state (EOS) to describe each material. These EOSs typically have physics-informed functional form adjustable parameters that calibrated in order replicate small-scale data. However, because the calibration data uncertainty and there inherent degeneracies fitting EOS, actually multiple might be consistent In this work, we perform quantification (UQ) for reactant product equations of state high explosive PBX 9501...

There are many well-known differences in the physical and chemical properties of ozone (O3) sulfur dioxide (SO2). O3 has longer weaker bonds than O2, whereas SO2 shorter stronger SO. The O–O2 bond is dramatically O–SO bond, singlet–triplet gap more double that O3. In addition, a very reactive species, while far less so. These disparities have been attributed to variations amount diradical character two molecules. this work, we use generalized valence (GVB) theory characterize electronic...

Inverse methods of statistical mechanics are becoming productive tools in the design materials with specific microstructures or properties.

Restricting the number of attractive physical "bonds" that can form between particles in a fluid suppresses usual demixing phase transition to very low particle concentrations, allowing for formation open, percolated, and homogeneous states, aptly called equilibrium or "empty" gels. Most demonstrations this concept have directly limited microscopic valence via anisotropic (patchy) attractions; however, an alternative macroscopic limitation would be desirable greater experimental tunability...

Inverse design was used to discover an isotropic pair interaction that assembles particles into inhomogeneous fluid matrix surrounding pores of prescribed size and morphology.

One emerging approach for the fabrication of complex architectures on nanoscale is to utilize particles customized intrinsically self-assemble into a desired structure. Inverse methods statistical mechanics have proven particularly effective discovery interparticle interactions suitable this aim. Here we evaluate generality and robustness recently introduced inverse design strategy [Lindquist et al., J. Chem. Phys. 145, 111101 (2016)] by applying simulated-based, machine learning method...

Many physics models have tunable parameters that are calibrated by matching the model output to experimental or calculated data. However, given calibration data often contain uncertainty and different parameter sets might result in a very similar simulated for finite set, it is advantageous provide an ensemble of consistent with Uncertainty quantification (UQ) provides means generate such statistically rigorous fashion. In this work, we perform UQ multi-phase equation state (EOS) carbon...

Equations of state (EOSs) are typically represented as physics-informed models with tunable parameters that adjusted to replicate calibration data closely possible. Uncertainty quantification (UQ) allows for the development an ensemble EOS consistent instead a single EOS. In this work, we perform UQ reactant and product EOSs variety high explosives (HEs). doing so, demonstrate strategy dealing heterogeneous (both experimental calculated) data. We also use statistical distance metric quantify...

The nitrile (Ctriple bondN) group is a powerful probe of structure and dynamics because its vibrational frequency extraordinarily sensitive to the electrostatic chemical characteristics local environment. For example, site-specific labels are useful indicators protein their infrared (IR) absorption spectra can clearly distinguish between solvent-exposed residues buried in hydrophobic core protein. In this work, three variants optimized quantum mechanics/molecular mechanics (OQM/MM) technique...

Porous mesophases, where well-defined particle-depleted 'void' spaces are present within a particle-rich background fluid, can be self-assembled from colloidal particles interacting via isotropic pair interactions with competing attractions and repulsions. While such structures could of wide interest for technological applications (e.g., filtration, catalysis, absorption, etc.), relatively few studies have investigated the that lead to these morphologies how they compare those produce other...

We discuss how a machine learning approach based on relative entropy optimization can be used as an inverse design strategy to discover isotropic pair interactions that self-assemble single- or multicomponent particle systems into Frank-Kasper phases. In doing so, we also gain insights the self-assembly of quasicrystals.

Low-density "equilibrium" gels that consist of a percolated, kinetically arrested network colloidal particles and are resilient to aging can be fabricated by restricting the number effective bonds form between colloids. Valence-restricted patchy have long served as one archetypal example such materials, but equilibrium also realized through synthetically simpler scalable strategy introduces secondary linker, small ditopic molecule, mediate Here, we consider case where linker molecules...

Integrated within an appropriate theoretical framework, molecular dynamics (MD) simulations are a powerful tool to complement experimental studies of solvation dynamics. Together, experiment, theory, and simulation have provided substantial insight into the dynamic behavior polar solvents. MD investigations especially valuable when applied heterogeneous environments found in biological systems, where calculated response environment electrostatic perturbation probe molecule can easily be...

The product of SF2 dimerization is an unusual molecule with many unexpected properties. For instance, there are four nonequivalent SF bond lengths, and they not inversely correlated their respective dissociation energies. Further, the minimum energy pathway to into two molecules does involve breaking longest or weakest bond. In this paper, we provide compelling explanations for both these observations by analyzing generalized valence (GVB) wave function FSSF3.