Valentina Piermarini

State and orientation selected reactivity of O(1D) + HCl from wavepacket calculations⁄

State and orientation selected reaction properties of O(1D) + HCl have been calculated using a wavepacket method and a recently proposed potential energy surface. The effect of increasing translational, rotational and vibrational energy on the reactivity of the system has been investigated. A non-negligible effect of the orientation of the target molecule on the efficiency of the reaction process has also been found.

Computational granularity and parallel models to scale up reactive scattering calculations

The computational granularity is a key factor in determining the suitability of a parallel model for an efficient implementation of complex codes on concurrent processor architectures. The paper discusses these aspects with reference to various theoretical approaches to reactive scattering and to the scale up of related calculations.

Towards a Full Dimensional Exact Quantum Calculation of the Li + HF Reactive Cross Section

Quantum mechanical calculations of the probabilities of the Li + HF(v, j) → LiF(v′, j′) + H elementary reaction have been performed by distributing the computations on two large scale computing facilities and using two different high level approaches. The calculations have been performed for several values of the total angular momentum quantum number, a large batch of energies, and the relevant reactant rotational states in order to progress towards an evaluation of the reactive cross section to compare with the experiment. A particular emphasis is put on the role played by internal energy.

Parallel Models for Reactive Scattering Calculations

The task of articulating some computer programs aimed at calculating reaction probabilities and reactive cross sections of elementary atom diatom reactions as concurrent computational processes is discussed. Various parallelization issues concerned with memory and CPU requirements of the different parallel models when applied to two classes of approach to the integration of the Schrodinger equation describing atom diatom elementary reactions are addressed. Particular attention is given to the importance of computational granularity for the choice of the model.

Time-Dependent Techniques

Practical aspects of quantum time-dependent calculations of atom-diatom reactive probabilities are discussed. The tutorial describes an application to the collinear H + H2 reaction, to its deuterium isotopic variant and to its zero total angular momentum three dimensional version.

Parallel Approaches to the Integration of the Differential Equations for Reactive Scattering

Parallel restructuring of computational codes devoted to the calculation of reactive cross sections for atom-diatom reactions plays an important role in exploiting the potentialities of concurrent platforms. Our reactive scattering codes have been parallelized on different platforms using MPI and performances have been evaluated to figure out the most efficient organization models. The same codes have been used for testing new parallel environments and related coordination languages.