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## Full-Text Articles in Physics

Direct Observation Of H_{2} Binding To A Metal Oxide Surface, J. Z. Larese, T. Arnold, L. Frazier, R. J. Hinde, A. J. Ramirez-Cuesta

#### Direct Observation Of H2 Binding To A Metal Oxide Surface, J. Z. Larese, T. Arnold, L. Frazier, R. J. Hinde, A. J. Ramirez-Cuesta

*Chemistry Publications and Other Works*

Inelastic neutron scattering is used to probe the dynamical response of H_{2} films adsorbed on MgO(100) as a function of film thickness. Concomitant diffraction measurements and a reduced-dimensionality quantum dynamical model provide insight into the molecule-surface interaction potential. At monolayer thickness, the rotational motion is strongly influenced by the surface, so that the molecules behave like quasiplanar rotors. These findings have a direct impact on understanding how molecular hydrogen binds to the surface of materials used in catalytic and storage applications.

A Six-Dimensional H_{2}–H_{2} Potential Energy Surface For Bound State Spectroscopy, Robert Hinde

#### A Six-Dimensional H2–H2 Potential Energy Surface For Bound State Spectroscopy, Robert Hinde

*Chemistry Publications and Other Works*

We present a six-dimensional potential energy surface for the (H_{2})_{2} dimer based on coupled-cluster electronic structure calculations employing large atom-centered Gaussian basis sets and a small set of midbond functions at the dimer’s center of mass. The surface is intended to describe accurately the bound and quasibound states of the dimers (H_{2})_{2}, (D_{2})_{2}, and H_{2}–D_{2} that correlate with H_{2} or D_{2} monomers in the rovibrational levels (*v*, *j*) =(0,0), (0,2), (1,0), and (1,2). We employ a close-coupled approach to compute the energies of these ...

Interaction-Induced Dipole Moment Of The Ar–H_{2} Dimer: Dependence On The H_{2} Bond Length, Robert J. Hinde

#### Interaction-Induced Dipole Moment Of The Ar–H2 Dimer: Dependence On The H2 Bond Length, Robert J. Hinde

*Chemistry Publications and Other Works*

We present ab initio calculations of the interaction-induced dipole moment of the Ar–H_{2} van der Waals dimer. The primary focus of our calculations is on the H_{2} bond length dependence of the dipole moment, which determines the intensities of both the collision-induced H_{2} = 1 ← 0 fundamental band in gaseous Ar–H_{2} mixtures and the dopant-induced H_{2} = 1 ← 0 absorption feature in Ar-doped solid H_{2} matrices. Our calculations employ large atom-centered basis sets, diffuse bond functions positioned between the two monomers, and a coupled cluster treatment of valence electron correlation; core-valence correlation effects appear ...

Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert J. Hinde

#### Population Size Bias In Descendant-Weighted Diffusion Quantum Monte Carlo Simulations, G. Lee Warren, Robert J. Hinde

*Chemistry Publications and Other Works*

We consider the influence of population size on the accuracy of diffusion quantum Monte Carlo simulations that employ descendant weighting or forward walking techniques to compute expectation values of observables that do not commute with the Hamiltonian. We show that for a simple model system, the *d*-dimensional isotropic harmonic oscillator, the population size must increase rapidly with *d* in order to ensure that the simulations produce accurate results. When the population size is too small, expectation values computed using descendant-weighted diffusion quantum Monte Carlo simulations exhibit significant systematic biases.

Vibrational Dependence Of The H_{2}–H_{2} *C*_{6} Coefficients, Robert Hinde

#### Vibrational Dependence Of The H2–H2 C6 Coefficients, Robert Hinde

*Chemistry Publications and Other Works*

We use the sum-over-states formalism to compute the imaginary-frequency dipole polarizabilities for H_{2}, as a function of the H–H bond length, at the full configuration interaction level of theory using atom-centered d-aug-cc-pVQZ basis sets. From these polarizabilities, we obtain isotropic and anisotropic *C*_{6} dispersion coefficients for a pair of H_{2} molecules as functions of the two molecules’ bond lengths.

Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde

#### Infrared-Active Vibron Bands Associated With Substitutional Impurities In Solid Parahydrogen, Robert Hinde

*Chemistry Publications and Other Works*

We present a model for the line shapes of infrared-active Q_{1}(0) vibron bands observed in solid parahydrogen doped with low concentrations of spherical substitutional impurities. The line shapes are highly sensitive to the H_{2} vibrational dependence of the dopant–H_{2} interaction. When this vibrational dependence is strong, the dopant can trap the infrared-active vibron in its first solvation shell; in this case, the trapped vibron manifests itself in the absorption spectrum as a narrow feature to the red of the pure solid’s vibron band.

The He-Lih Potential Energy Surface Revisited. I. An Interpolated Rigid Rotor Surface, Robert Hinde

#### The He-Lih Potential Energy Surface Revisited. I. An Interpolated Rigid Rotor Surface, Robert Hinde

*Chemistry Publications and Other Works*

We reconsider the potential energy surface of the He–LiH system recently examined by Gianturco and co-workers [F. A. Gianturco et al., Chem. Phys. **215**, 227 (1997)]. We compute the He–LiH interaction energy at the CCSD(T) level using large correlation consistent atomic basis sets supplemented with bond functions. To capture the severe anisotropy of the He–LiH potential, we interpolate our ab initio points in the angular direction with cubic splines, then expand the splines in terms of Legendre polynomials. The resulting smooth potential surface differs substantially from that of Gianturco et al.; in particular, our attractive He ...