Understanding oxide ion transport in cation-ordered yttria-stabilized zirconia.

Classical molecular dynamics simulations are carried out on cationically ordered yttria-doped zirconia, YZrO, at the dopant (Y) concentration of = 12.5%. A variety of Zr/Y ordered structures are examined for local migration pathways and microscopic energetics governing oxide ion transport in the system.

Ab initio molecular dynamics investigation of structural, dynamic and spectroscopic aspects of Se(vi) species in the aqueous environment.

Microscopic investigation of solvation of selenic acid (H2SeO4) in the aqueous environment has been carried out using the Car-Parrinello molecular dynamics simulation technique. The species deprotonates to HSeO4(-) in a few picoseconds owing to its low pKa1 value of -3.0.

Hydration, swelling, interlayer structure, and hydrogen bonding in organolayered double hydroxides: insights from molecular dynamics simulation of citrate-intercalated hydrotalcite.

Molecular dynamics (MD) simulation of the Mg/Al (3:1) layered double hydroxide (LDH), hydrotalcite (HT), containing citrate, C6H5O7(3-), as the charge balancing interlayer anion provides new molecular scale insight into the interlayer structure, hydrogen bonding, and energetics of the hydration and consequent swelling of LDH compounds containing organic and biomolecules. Citrate-HT exhibits affinity for water up to very high hydration levels, in contrast to the preferred low hydration states of most LDHs intercalated with small, inorganic anions. This result is consistent with the recent experimental observation of the delamination of lactate-HT.

Understanding hydrogen scrambling and infrared spectrum of bare CH5+ based on ab initio simulations.

A comprehensive study of the properties of protonated methane obtained from ab initio molecular dynamics simulations is presented. Comparing computed infrared spectra to the measured one gives further support to the high fluxionality of bare CH(5)(+). The computational trick to partially freezing out large-amplitude motion, in particular hydrogen scrambling and internal rotation of the H(2) moiety, leads to an understanding of the measured IR spectrum despite the underlying rapid hydrogen scrambling motion that interconverts dynamically structures of different symmetry and chemical bonding pattern.

Understanding the infrared spectrum of bare CH5+.

Protonated methane, CH5+, continues to elude definitive structural assignment, as large-amplitude vibrations and hydrogen scrambling challenge both theory and experiment. Here, the infrared spectrum of bare CH5+ is presented, as detected by reaction with carbon dioxide gas after resonant excitation by the free electron laser at the FELIX facility in the Netherlands. Comparison of the experimental spectrum at approximately 110 kelvin to finite-temperature infrared spectra, calculated by ab initio molecular dynamics, supports fluxionality of bare CH5+ under experimental conditions and provides a dynamical mechanism for exchange of hydrogens between CH3 tripod positions and the three-center bonded H2 moiety, which eventually leads to full hydrogen scrambling.

Quantum corrections to classical time-correlation functions: hydrogen bonding and anharmonic floppy modes.

Several simple quantum correction factors for classical line shapes, connecting dipole autocorrelation functions to infrared spectra, are compared to exact quantum data in both the frequency and time domain. In addition, the performance of the centroid molecular dynamics approach to line shapes and time-correlation functions is compared to that of these a posteriori correction schemes. The focus is on a tunable model that is able to describe typical hydrogen bonding scenarios covering continuously phenomena from tunneling via low-barrier hydrogen bonds to centered hydrogen bonds with an emphasis on floppy modes and anharmonicities.