Krarupdrejer2629

The corresponding value of the thermal conductivity agrees well with experiments.We present a semianalytical theory for the exciton transport in organic molecular crystals interacting strongly with a single cavity mode. Based on the Holstein-Tavis-Cummings model and the Kubo formula, we derive an exciton mobility expression in the framework of a temperature-dependent variational canonical transformation, which can cover a wide range of exciton-vibration coupling, exciton-cavity coupling, and temperatures. A closed-form expression for the coherent part of the total mobility is obtained in the zeroth order of the exciton-vibration coupling, which demonstrates the significance of vibrationally dressed dark excitons in the determination of the transport mechanism. By performing numerical simulations on both the H- and J-aggregates, we find that the exciton-cavity coupling has significant effects on the total mobility (1) At low temperatures, there exists an optimal exciton-cavity coupling strength for the H-aggregate at which a maximal mobility is reached, while the mobility in the J-aggregate decreases monotonically with an increase in the exciton-cavity coupling and (2) at high temperatures, the mobility in both types of aggregates get enhanced by the cavity. We illustrate the above-mentioned low-temperature optimal mobility observed in the H-aggregate by using realistic parameters at room temperature.The vacuum-ultraviolet threshold photoelectron spectrum of methyl isocyanate CH3NCO has been recorded from 10.4 eV to 12 eV using synchrotron radiation and a coincidence technique allowing for a mass-discrimination of the photoelectron signal. A significant improvement is achieved over previous investigations as this experimental setup leads to a much more resolved spectrum. Ten sharp peaks and a broad feature spanning 1.2 eV were recorded. This spectrum consists of X̃+ 2A″←X̃ 1A' and Ã+ 2A'←X̃ 1A' ionizing transitions. For the former, the adiabatic ionization energy was determined experimentally to be 10.596(6) eV; for the latter, its value was estimated to be 10.759(50) eV. Seven sharp peaks could be assigned to vibrational modes of the cation X̃+ 2A″ and neutral X̃ 1A' ground electronic states involving only the NCO group atoms. Theoretical modeling of the threshold photoelectron spectrum has proven difficult as methyl isocyanate is a non-rigid molecule displaying large amplitude internal rotation of the methyl group and ∠CNC bending mode, leading to the quasi-symmetry. With the help of ab initio calculations, a theoretical model in which these two large amplitude motions are included in addition to the five small amplitude vibrational modes involving NCO group atoms is proposed. Comparison with the experimental spectrum shows that the broad feature and the strongest peak line positions are well accounted for; their intensities are also fairly well reproduced after adjusting a few parameters.We present efficient yet rigorous, full-dimensional quantum bound-state calculations of the fully coupled J = 0 and one intra- and intermolecular rovibrational levels of H2O-CO and D2O-CO complexes. The new ab initio nine-dimensional (9D) potential energy surface (PES) [Y. Liu and J. Li, Phys. Chem. Chem. Phys. 21, 24101 (2019)] is employed. In the spirit of the recently introduced general procedure [P. M. Felker and Z. Bačić, J. Chem. Phys. 151, 024305 (2019)], the 9D rovibrational Hamiltonian is partitioned into a 5D (rigid-monomer) intermolecular Hamiltonian, two intramolecular vibrational Hamiltonians-one for the water monomer (3D) and another for the CO monomer (1D), and a 9D remainder term. The low-energy eigenstates of the three reduced-dimension Hamiltonians are used to build up the 9D product contracted basis, in which the matrix of the full rovibrational Hamiltonian is diagonalized. In line with the findings of our earlier study referenced above, the 5D intermolecular eigenstates included in the 9D enstates. Also examined is the extent of the eigenstate delocalization over the two minima on the PES. Whenever possible, a comparison is made with the experimental data in the literature.The Lennard-Jones (LJ) potential is perhaps one of the most widely used models for the interaction of uncharged particles, such as noble gas solids. The phase diagram of the classical LJ solid is known to exhibit transitions between hcp and fcc phases. However, the phase behavior of the quantum LJ solid remains unknown. mTOR inhibitor Thermodynamic integration based on path integral molecular dynamics (PIMD) and lattice dynamics calculations are used to study the phase stability of the hcp and fcc LJ solids. The hcp phase is shown to be stabilized by quantum effects in PIMD, while fcc is shown to be favored by lattice dynamics, which suggests a possible re-entrant low pressure fcc phase for highly quantum systems. Implications for the phase stability of noble gas solids are discussed. For parameters equating to helium, the expansion due to zero-point vibrations is associated with quantum melting neither crystal structure is stable at zero pressure.Nanoporous materials are promising as the next generation of absorbents for gas storage and separation with ultrahigh capacity and selectivity. The recent advent of data-driven approaches in materials modeling provides alternative routes to tailor nanoporous materials for customized applications. Typically, a data-driven model requires a large amount of training data that cannot be generated solely by experimental methods or molecular simulations. In this work, we propose an efficient implementation of classical density functional theory with a graphic processing unit (GPU) for the fast yet accurate prediction of gas adsorption isotherms in nanoporous materials. In comparison to serial computing with the central processing unit, the massively parallelized GPU implementation reduces the computational cost by more than two orders of magnitude. The proposed algorithm renders new opportunities not only for the efficient screening of a large materials database for gas adsorption but it may also serve as an important stepping stone toward the inverse design of nanoporous materials tailored to desired applications.