The Virtual Atomic and Molecular Data Centre (VAMDC) Consortium is a worldwide consortium which federates atomic and molecular databases through an e-science infrastructure and an organisation to support this activity. About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for modelling in many fields of astrophysics. Recently the VAMDC Consortium has connected databases from the radiation damage and the plasma communities, as well as promoting the publication of data from Indian institutes. This paper describes how the VAMDC Consortium is organised for the optimal distribution of atomic and molecular data for scientific research. It is noted that the VAMDC Consortium strongly advocates that authors of research papers using data cite the original experimental and theoretical papers as well as the relevant databases.

The scattering of atomic nitrogen over a N-pre-adsorbed W(100) surface is theoretically described in the case of normal incidence off a single adsorbate. Dynamical reaction mechanisms, in particular Eley-Rideal (ER) abstraction, are scrutinized in the 0.1-3.0 eV collision energy range and the influence of temperature on reactivity is considered between 300  and 1500 K. Dynamics simulations suggest that, though non-activated reaction pathways exist, the abstraction process exhibits a significant collision energy threshold (0.5 eV). Such a feature, which has not been reported so far in the literature, is the consequence of a repulsive interaction between the impinging and the pre-adsorbed nitrogens along with a strong attraction towards the tungsten atoms. Above threshold, the cross section for ER reaction is found one order of magnitude lower than the one for hot-atoms formation. The abstraction process involves the collision of the impinging atom with the surface prior to reaction but temperature effects, when modeled via a generalized Langevin oscillator model, do not affect significantly reactivity.

Quasiclassical trajectories simulations are performed to study the influence of surface temperature on the dynamics of a N atom colliding a N-preadsorbed W(100) surface under normal incidence. A generalized Langevin surface oscillator scheme is used to allow energy transfer between the nitrogen atoms and the surface. The influence of the surface temperature on the N(2) formed molecules via Eley-Rideal recombination is analyzed at T = 300, 800, and 1500 K. Ro-vibrational distributions of the N(2) molecules are only slightly affected by the presence of the thermal bath whereas kinetic energy is rather strongly decreased when going from a static surface model to a moving surface one. In terms of reactivity, the moving surface model leads to an increase of atomic trapping cross section yielding to an increase of the so-called hot atoms population and a decrease of the direct Eley-Rideal cross section. The energy exchange between the surface and the nitrogen atoms is semi-quantitatively interpreted by a simple binary collision model.

The potential energy surface (PES) of a molecular system constitutes a cornerstone for nearly every theoretical study of spectroscopy and dynamics. We present here AUTOSURF, our freely distributed code for the automated construction of PESs. This first release treats van der Waals systems composed of two rigid fragments. A version for reactive systems with up to five atoms is under development. The AUTOSURF suite is designed to completely automate all of the steps and procedures that go into fitting various classes of PESs and facilitates certain PES refinements aimed toward specific applications in spectroscopy and dynamics. The algorithms are based on a local interpolating moving least-squares methodology and have many advanced features such as iterative refinement and symmetry recognition. The code interfaces to popular electronic structure codes such as MOLPRO and GAUSSIAN to automatically generate ab initio PESs and is well-suited for treating highly anisotropic interactions which are challenging for traditional quadrature type expansions. The niche of these algorithms is to obtain an interpolative representation of high-level electronic energies with negligible (arbitrarily small) fitting error, requiring minimal human supervision in the entire process of selection, computation, and fitting of the ab initio data. The code is designed to run in parallel on Linux-based machines ranging from small workstations to large high-performance computing clusters.

Quasiclassical molecular dynamics simulations are performed to study the Eley–Rideal recombination of H2 on two crystallographic planes of tungsten. Potential energy surfaces, based on density functional theory, are used to describe the H+H/W(100, 110) interactions. The calculations are carried out within the single adsorbate limit under normal incidence of the impinging H atoms. The influence of the crystallographic anisotropy on reaction cross sections and energy distribution of the formed molecules is analyzed in detail. Despite some discrepancies in the dynamics of recombination between W(100) and W(110) surfaces, translational, rotational, and vibrational energies of the formed molecules do not depend significantly on surface symmetry. Vibrational distribution of formed H2 molecules are found in good agreement with experiments.

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The first chiral interstellar organic molecule, propylene oxide (CH 3 CHCH 2 O), was detected recently toward the galactic center. Accurate determination of its abundance relies on the knowledge of collisional cross sections. We investigate here the rotational excitation of propylene oxide induced by collisions with helium. The calculations are based on a three-dimensional CH 3 CHCH 2 O−He potential energy surface computed using the explicitly correlated coupled-cluster theory extended to the complete basis set limit [CCSD(T)-F12b/CBS]. The interaction energies are fitted using an interpolating moving least squares method, and this potential is refitted using a partial wave expansion based on spherical harmonics. Rotational cross sections are obtained at the quantum close-coupling level for a collision energy of 10 cm −1 . Convergence issues and collisional propensity rules are discussed.

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