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Accueil > FR > Recherche > Physique des Atomes Froids > Séminaire du groupe

Daniel PELAEZ RUIZ (Laboratoire PhLAM, équipe PCMT)

publié le

Le 22 Février 2018 - 11h - salle 252 (salle du Conseil) bat. P5 bis

Representation of the potential energy surface in the quantum dynamical study of high-dimensional molecular systems.

The quantum description of nuclear motion is usually obtained by mapping the system onto a grid [1]. This implies a discretisation of the configuration space and, in turn, the expression of all quantities in the form of high-order tensors. Unfortunately, multidimensional representations imply an exponential scaling of data and operations with system size as well as the difficulty of computing multidimensional integrals [2].

Solutions to these issues, in particular when considering the representation of the potential energy surface, exist in the form of tensor-decomposition schemes. We present the recently developed the Multigrid POTFIT (MGPF) algorithm [3] which alleviates the exponential scaling by avoiding the calculations on the full grid. Moreover, we introduce our latest improvements to the algorithm which provide numerical stability and higher accuracy through the use of non-product grids [4].

The MGPF algorithm has been used in conjunction with the Multiconfiguration Time-Dependent Hartree method for the full-dimensional (9D) study of the vibrational structure and the computation of the infrared spectrum of the hydrated hydroxide anion (H3O2-) [5].

References :
[1] Fabien Gatti (Ed.) in Molecular Quantum Dynamics From Theory to Applications.
Springer (2014).
[2] H.-D. Meyer, F. Gatti, G. A. Worth (Eds.) Multidimensional Quantum Dynamics : MCTDH
Theory and Applications, Wiley (2009).
[3] D. Peláez, H.-D. Meyer, The multigrid POTFIT (MGPF) method : Grid representations of
potentials for quantum dynamics of large systems, J. Chem. Phys., 138, 014108 (2013).
[4] D. Peláez, H.-D. Meyer (in preparation)
[5] D. Peláez, H.-D. Meyer, On the Infrared Absorption Spectrum of the Hydrated Hydroxide (H3O2-), Chem. Phys. 482, 100 (2017)