We extend the statistical associating fluid theory of quantum corrected Mie potentials (SAFT-VRQ Mie), previously developed for pure fluids [Aasen et al., J. Chem. Phys. 151, 064508 (2019)], to fluid mixtures. In this model, particles interact via Mie potentials with Feynman-Hibbs quantum corrections of first order (Mie-FH1) or second order (Mie-FH2). This is done using a third-order Barker-Henderson expansion of the Helmholtz energy from a non-additive hard-sphere reference system. We survey existing experimental measurements and ab initio calculations of thermodynamic properties of mixtures of neon, helium, deuterium, and hydrogen and use them to optimize the Mie-FH1 and Mie-FH2 force fields for binary interactions. Simulations employing the optimized force fields are shown to follow the experimental results closely over the entire phase envelopes. SAFT-VRQ Mie reproduces results from simulations employing these force fields, with the exception of near-critical states for mixtures containing helium. This breakdown is explained in terms of the extremely low dispersive energy of helium and the challenges inherent in current implementations of the Barker-Henderson expansion for mixtures. The interaction parameters of two cubic equations of state (Soave-Redlich-Kwong and Peng-Robinson) are also fitted to experiments and used as performance benchmarks. There are large gaps in the ranges and properties that have been experimentally measured for these systems, making the force fields presented especially useful.Quantum coherence plays an important role in exciton dynamics such as singlet fission, which may be determined by molecular physical properties, including energy levels, electronic couplings, and electron-phonon couplings, and by geometric properties, including packing configuration and exciton delocalization. However, the global picture of quantum coherence in high-dimensional multistate systems is still blurred. Here, we perform nonadiabatic molecular dynamics simulation for singlet fission in tetracene clusters and demonstrate that the topology of quantum coherence in terms of the global structure of the coupled multistate system may significantly modulate fission dynamics. In particular, quantum coherence in the spin-specified models could be protected by its topological structure from external perturbations. Our work suggests that the topology of quantum coherence is indispensable in the understanding and control of quantum dynamics, which may find potential implementations to singlet fission and quantum computation.Valence-to-core x-ray emission spectroscopy (VtC XES) combines the sample flexibility and element specificity of hard x-rays with the chemical environment sensitivity of valence spectroscopy. We extend this technique to study geometric and electronic structural changes induced by photoexcitation in the femtosecond time domain via laser-pump, x-ray probe experiments using an x-ray free electron laser. The results of time-resolved VtC XES on a series of ferrous complexes [Fe(CN)2n(2, 2'-bipyridine)3-n]-2n+2, n = 1, 2, 3, are presented. Comparisons of spectra obtained from ground state density functional theory calculations reveal signatures of excited state bond length and oxidation state changes. An oxidation state change associated with a metal-to-ligand charge transfer state with a lifetime of less than 100 fs is observed, as well as bond length changes associated with metal-centered excited states with lifetimes of 13 ps and 250 ps.The interplay between Brownian colloidal particles and their suspending fluid is well understood since Einstein's seminal work of 1905 the fluid consists of atoms whose thermal motion gives rise to the Brownian motion of the colloids, while the colloids increase the viscosity of the suspension under shear. An alternative route to the viscosity, by exploring the thermal stress fluctuations in a quiescent fluid in the Green-Kubo formalism, however, reveals a marked inconsistency with the viscosity under shear. We show that an additional stress term, accounting for Brownian fluctuating stresslets and coupled to the Brownian forces by a generalized fluctuation-dissipation theorem, is required for the description of the stress and viscosity of a colloidal suspension. Whereas previous applications of the Green-Kubo method to colloidal systems were limited to the deterministic "thermodynamic" part of the stress, using other means to determine the remainder of the viscosity, the whole viscosity is now within the reach of equilibrium studies.Finding an optimal match between two different crystal structures underpins many important materials science problems, including describing solid-solid phase transitions and developing models for interface and grain boundary structures. In this work, we formulate the matching of crystals as an optimization problem where the goal is to find the alignment and the atom-to-atom map that minimize a given cost function such as the Euclidean distance between the atoms. We construct an algorithm that directly solves this problem for large finite portions of the crystals and retrieves the periodicity of the match subsequently. We demonstrate its capacity to describe transformation pathways between known polymorphs and to reproduce experimentally realized structures of semi-coherent interfaces. Additionally, from our findings, we define a rigorous metric for measuring distances between crystal structures that can be used to properly quantify their geometric (Euclidean) closeness.The equation of state, dynamical properties, and molecular-scale structure of squalane and mixtures of poly-α-olefins at room temperature are studied with a combination of state-of-the-art, high-pressure experiments and molecular-dynamics simulations. Eganelisib datasheet Diamond-anvil cell experiments indicate that both materials are non-hydrostatic media at pressures above ∼1 GPa. The equation of state does not exhibit any sign of a first-order phase transition. High-pressure x-ray diffraction experiments on squalane show that there are no Bragg peaks, and hence, the apparent solidification occurs without crystallization. These observations are complemented by a survey of the equation of state and dynamical properties using simulations. The results show that molecular diffusion is essentially arrested above about 1 GPa, which supports the hypothesis that the samples are kinetically trapped in metastable amorphous-solid states. The shear viscosity becomes extremely large at very high pressures, and the coefficient governing its increase from ambient pressure is in good agreement with the available literature data.