Potential energy surface

About: Potential energy surface is a research topic. Over the lifetime, 11674 publications have been published within this topic receiving 307691 citations.

A six-dimensional H2-H2 potential energy surface for bound state spectroscopy

Abstract: We present a six-dimensional potential energy surface for the H2-H2 dimer based on ab initio electronic structure calculations. The surface is intended to describe accurately the bound and quasibound states of the dimers H2-H2, D2-D2, and H2-D2 that correlate with H2 or D2 monomers in the rovibrational levels (v, j) = (0, 0), (0, 2), (1, 0), and (1, 2). We use four experimentally measured transition energies for these dimers to make two empirical adjustments to the ab initio surface; the adjusted surface gives computed transition energies for 56 experimentally observed transitions that agree with experiment to within 0.036 cm^{-1}. For 29 of the 56 transitions, the agreement between the computed and measured transition energies is within the quoted experimental uncertainty. We use our potential energy surface to predict the energies of another 34 not-yet-observed infrared and Raman transitions for the three dimers.

Energetics and dynamics of H(2) adsorbed in a nanoporous material at low temperature.

Abstract: Molecular hydrogen adsorption in a nanoporous metal-organic framework structure (MOF-74) is studied via van der Waals density-functional calculations. The primary and secondary binding sites for H(2) are confirmed. The low-lying rotational and translational energy levels are calculated, based on the orientation and position dependent potential energy surface at the two binding sites. A consistent picture is obtained between the calculated rotational-translational transitions for different H(2) loadings and those measured by inelastic neutron scattering exciting the singlet to triplet (para to ortho) transition in H(2). The H(2) binding energy after zero-point energy correction due to the rotational and translational motions is predicted to be approximately 100 meV in good agreement with the experimental value of approximately 90 meV.

Enhancing dissociative chemisorption of H2O on Cu(111) via vibrational excitation

Abstract: The dissociative chemisorption of water is an important step in many heterogeneous catalytic processes. Here, the mode selectivity of this process was examined quantum mechanically on a realistic potential energy surface determined by fitting planewave density functional calculations spanning a large configuration space. The quantum dynamics of the surface reaction were characterized by a six-dimensional model including all important internal coordinates of H2O and its distance to the surface. It was found that excitations in all three vibrational modes are capable of enhancing reactivity more effectively than increasing translational energy, consistent with the “late” transition state in the reaction path.

Quantum dynamics of the H+CH4→H2+CH3 reaction in curvilinear coordinates: Full-dimensional and reduced dimensional calculations of reaction rates

Abstract: Full-dimensional quantum dynamics calculations for the H+CH4→H2+CH3 reaction using curvilinear coordinates are presented. A curvilinear coordinate system to describe reactions of the type X+YCH3→XY+CH3 is developed which facilitates efficient calculations using the multiconfigurational time-dependent Hartree (MCTDH) approach. To describe the bending motion of the X and Y atoms relative to the axis defined by the CH3 fragment, coordinates based on stereographic projection are introduced. These coordinates yield a kinetic energy operator free of singularities within the dynamically relevant region. Employing this curvilinear coordinate system, full-dimensional and reduced dimensional MCTDH calculations study the cumulative reaction probability (for J=0) and the thermal rate constant for the H+CH4 reaction on the Jordan-Gilbert potential energy surface [J. Chem. Phys. 102, 5669 (1995)]. The full-dimensional results agree very well with previous full-dimensional MCTDH results which used transition state based...

Exploring the reaction dynamics of nitrogen atoms: A combined crossed beam and theoretical study of N(2D)+D2→ND+D

Abstract: In the first successful reactive scattering study of nitrogen atoms, the angular and velocity distribution of the ND product from the reaction N(2D)+D2 at 5.1 and 3.8 kcal/mol collision energies has been obtained in a crossed molecular beam study with mass spectrometric detection. The center-of-mass product angular distribution is found to be nearly backward–forward symmetric, reflecting an insertion dynamics. About 30% of the total available energy goes into product translation. The experimental results were compared with those of quasiclassical trajectory calculations on an accurate potential energy surface obtained from large scale ab initio electronic structure computations. Good agreement was found between the experimental results and the theoretical predictions.