Intitiative de Recherche Stratégique Programme PSI2

Paris-Saclay University

Quantum Dynamics with the Multi-Configuration Time-Dependent Hartree (MCTDH) method : future and perspectives

This program will focus on quantum dynamics and more precisely on the future of the Multi Configuration Time Dependent Hartree (MCTDH) approach, one of the most successful methods to propagate multidimensional wavepackets and will cover a collection of important topics where chemistry and physics strongly overlap. MCTDH has been applied to very different fields: heterogeneous catalysis, reactive or non-reactive collisions, infrared spectroscopy, ultraviolet spectroscopy involving, or not, non-Born-Oppenheimer processes, photochemistry, processes guided by laser pulses, optimal control. The new variants MCTDHB and MCTDHF open the possibility to simulate the dynamics of Bosonic and Fermionic systems, respectively, in a systematic way. Several codes, that use the MCTDH approach have been developed independently, the most general one being the Heidelberg MCTDH package. MCTDH is at a pivotal period in its history, when several questions are rising: how is it possible to keep the main package as general as possible and to include the developments of the other groups ? What is the future of the approach and the package? Is it possible to create an international consortium gathering all the main developers and offering an official framework for those who want to participate in the development of the program or simply wish to use one of the variants of MCTDH? The proposed program will address these questions and will last for four weeks: the first week dedicated to a school for students, two weeks of intensive collaborations and the last week dedicated to a formal meeting on the future of MCTDH.

The idea of the present PSI2 program arose out of several discussions between Fabien Gatti and Olivier Dulieu during the program "Universality in Few-Body Systems" at the Kavli Institute for Theoretical Physics in Santa-Barbara in November-December 2016.

Scientific coordinators :

-Fabien Gatti, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Saclay.

-Daniel Peláez-Ruiz, Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM), Université de Lille.

-Hans-Dieter Meyer, Institute of Physical Chemistry, Universität Heidelberg (Germany).

-Graham Worth, Department of Chemistry,University College London (UK).

Schedule:

Week 1: September 25-29 - School on MCTDH with lab sessions

During the first week, a school for students, postdocs or any researchers interested in using the MCTDH will be organized. Lab sessions will be organized at the Institute for Development and Resources in Intensive Scientific Computing (IDRIS). We plan other teachings and lab sessions on MCTDHB/F, vMCG. We will support students and young researchers to attend this school and to stay longer to start concrete projects with more experienced scientists. Please find more information on this explicatory poster.

Weeks 2 : October 2-6 The MCTDH approach to indistinguishable particles and ultrafast phenomena.

Keywords :"cold atoms", MCTDHB/F approaches, "ultra fast" phenomena (femtochemistry and attospectroscopy)

3: October 9-13  -From small molecules to complex molecular systems with MCTDH.

Keywords : "Molecular Spectroscopy", astrochemistry, quantum chemistry and expression on the Hamiltonian operators, Multigrid potfit, Multi-Layer potfit, new methods to express the potential energy surfaces in a sum of products  of low-dimensional functions.

Week 4: October 16-20 - Meeting on the future of MCTDH

The last week will be dedicated to a formal meeting on the future of MCTDH with short presentations and formal discussions on the different aspects of the future of MCTDH: all the different codes will be presented, the possibility to create a formal international consortium and the possibilities of interactions between the main groups of the MCTDH community will be discussed.

The middle two weeks are dedicated to intensive collaborations between the participants with, each day, informal seminars and discussions: they will stimulate strong interactions from members of the MCTDH community or other scientists, including experimentalists, who want to interact with this community. It will be an unique opportunity to get familiar with the different existing codes and to take stock of what is now available in the community.

Special emphasis will be placed on the possibilities of new collaborations with other communities in physics and chemistry with both theoreticians and experimentalists. Formal seminars and discussions will be organized to open interactions with specific communities: femtochemistry, attospectroscopy, cold atoms/molecules, Bosonics systems, Fermionic systems, biological systems, etc.