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The uncoupled anharmonic OH-stretching vibrational frequency for the layered mineral Mg[(OH).sub.2] (brucite) has been calculated in the pressure range 0-22 GPa. Quantum-mechanical electronic structure (DFT) calculations were performed, followed by quantum-mechanical vibrational energy calculations. The following findings emerged: (1) The calculated dv(OH)/dP slope is -4 [cm.sup.-1]/GPa, in agreement with the experimental literature value [taken as the average between the Raman and IR-measured slopes for Mg[(OH).sub.2]]. (2) The calculated v(OH) vs. R(O***O) correlation is linear and the slope is much smaller than that of traditional H-bond correlation curves in the literature. (3) The main origin of the small dv/dP and dv/dR(O***O) slopes is the small electric field variation as the mineral layers are pressed toward each other. (4) At high pressure, the OH- ions show s[O.sup.m]e tendency to be tilted with respect to the c axis, and a larger tilt angle leads to a larger v(OH) downshift. (5) The pressure variation of the D quadrupole coupling constant is approximately -1 kHz/GPa. Keywords: Brucite, anharmonic OH frequencies, high pressure, electric field, hydrogen bonding, correlation curve, hydrous mineral DOI: 10.2138/am.2009.3188

The DOS is downshifted when the substrate coverage is increased for all the interface models. The interfacial interaction arises from a charge redistribution within the components of the interface.

Theoretical extended x-ray absorption fine-structure (EXAFS) spectra are computed from molecular dynamics (MD) simulation data. Based on MD-generated geometries, EXAFS spectra are generated with the FEFF6 program, commonly used in the analysis of experimental EXAFS spectra.

Research has been conducted on the ab initio optimizations of o-, m- and p-C (sub)2 B (sub)10 H (sub)12 carborane cages. The energy difference between the protonated and deprotonated cages has been computed.

Experiments on the electronic property and structure of cerium oxide (CeO2) which had been doped with Ca are discussed. Cerium oxide in used in exhaust gas converters for cars and in the oil refining industry.

A study was conducted to analyze the solvent exchange mechanism around alkali cations in dilute aqueous solutions, specifically mechanisms associated with lithium ions and sodium ions. Molecular dynamics simulations were carried out at constant temperature and constant pressure for three systems. Experimental results indicated that most of the exchange process could be categorized. Findings also showed that water changes occurred more frequently around the sodium ion than around the lithium ion.

The classical molecular dynamics (MD) and quantum mechanics (QM) embedded-cluster calculations are combined to investigate the adsorption of CO on a dynamically distorted MgO(001) surface. The distribution of adsorption energies for CO above the Mg(super 2+) sites on the MgO(001) surface at 50, 80, and 150 K is predicted by using the linear expression.

A Car-Parrinello simulation of a single Fe(super 3+) ion in periodic box of 32 water molecules is presented. The aim is to investigate the hydration shell structure and water vibrations for the hydrated ferric ion.

The average Oh stretching vibrational frequency for the water molecules in the first hydration shell around a Li(super +) ion in a dilute aqueous solution is calculated by a hybrid molecular dynamics + quantum-mechanical ('MD+QM') approach. The average frequency at the B3LYP level of theory, including second- and third-shell effects as well as anharmonicity, falls at approximately 3380cm (super -1), and the calculated downshift is approximately -305 cm(super -1).

The structure and dynamics of water molecules around the Fe(super 2+) and Fe(super 3+) ions, as well as the ionic diffusion is discussed, using a new flexible water model (SPC+CCL) combined with ion-water potential. It is concluded that the flexible-water model SPC+CCL describes the structural properties and the diffusion equally well or better than the SPC/E water model for the Fe(super 2+)(ag) and Fe(super 3+)(ag) solutions.

The solvent exchange rate of aqueous Li (super+) was determined by employing the reactive flux method in combination with very long molecular dynamics simulations based on effective three-body ion-water potentials. The mechanisms for the resulting exchange events were studied in considerable details and analyzed in terms of the five commonly discussed exchange classes, associative (A), dissociative (D), and interchange (I, I (sub a), I (sub d).

Research into the structure of the hydrated calcium(II) ion in aqueous solution is presented. It was found to be possible to calculate realistic theoretical extended X-ray absorption fine structure spectroscopy spectra for aqueous calcium chloride solutions.

The use of neural networks to represent intermolecular potential functions was investigated. Feed-forward networks of different sizes were utilized to reproduce the three-body interaction energies in the molecular system H(sub 2)O-Al(super 3+)-H(sub 2)O. The three-body interaction terms were found to be necessary for an accurate description of the molecular system. Experimental results showed that a neural network representation of potential functions has certain advantages that outweigh the disadvantages in lack of interpretability or computing speed.