Describing nonequilibrium processes in molecular and condensed-phase systems continues to pose significant challenges due to the overwhelming computational costs of the structural and dynamical aspects of the problem. Yet, this is a problem that is increasingly topical, especially with the advent of attosecond lasers and ultrafast electron diffraction techniques that allow to visualize the “molecular movie”. Up to now, most of the methods to describe the correlated electron-nuclear motion have been based on the Born-Huang expansion that fails to meet the appropriate trade-off between accuracy and efficiency for large systems.
The results of BeBOP research have yield an efficient algorithm for performing ab-initio quantum dynamics simulations that is based on the conditional decomposition of the many-body wavefunction. This highly parallelizable technique achieves quantitative accuracy using orders of magnitude fewer trajectories than the corresponding mean-field calculation. The degree of computational efficiency of this method opens the possibility to treat dynamics in larger quantum systems with unprecedented accuracy and constitutes an alternative to available methods for systems of interacting fermions/bosons.
Furthermore, the developed method could also lead to a paradigm change in how nonadiabatic molecular dynamics is numerically approached: (i) unlike methods based on the Born-Huang expansion of the molecular wave function (e.g. Ab- Initio Multiple Spawning or Tully surface hopping), the developed tool provides direct access to electron dynamics, (ii) the newly derived method goes beyond standard time-dependent density-functional theory for fixed nuclei and accounts for electron-nuclear correlations beyond the time-dependent density-functional theory+Ehrenfest method.
We expect the new method to help understand important processes such as Joule heating in atomic devices, vision, photovoltaics, or proton transfer and hydrogen- storage. These processes include some of the most difficult phenomena to theoretically model, viz. an accurate calculation of the time-resolved dynamics of electrons and ions while their correlations and quantum features of the nuclear motion are critical.
Furthermore Dr. Albareda has been very active in the dissemination of results in numerous conferences and workshops (13) where he has given talks on his research topics (selected):
Participation to Conferences and Workshops
i. Coupled electron-nuclear dynamics without Born-Oppenheimer surfaces. XXXIII Scientific Meetings in the Mediterranean. 18th-20th October 2017 Mahó, Spain. Invited.
ii. Ab-initio nonadiabatic dynamics without Born-Oppenheimer potential-energy surfaces. Non-Adiabatic Quantum Dynamics: From Theory to Experiments. 2th-6th July 2018. Lausanne, Switzerland. Invited.
iii.Trajectory Approaches for Nonequilibrium Quantum Dynamics in Light-Matter Systems. Scientific Advisory Board Meeting of the MPSD. 9th-11th January 2019. Hamburg, Germany. Invited.
iv. Approaches to nonadiabatic quantum dynamics without potential-energy surfaces. Recent developments in quantum dynamics. 17th–21th July 2019. Lyon, France. Invited.
Contributions to Conferences and Workshops
i. Non-Universality of Quantum Dynamics Computed from Time-Correlation Functions. International Conference on Quantum Frontiers and Fundamentals. 30th April-4th May, 2018 Bengaluru, India. Talk.
ii. Eliminating quantum uncertainty in quantum electron devices: Leveraging classical and quantum computing. The International Workshop on Computational Nanotechnology. 20th-24th May 2019 Illinois, USA. Talk
iii. Biradical Species induced by Valence Tautomerism: a challenge for Electronic Structure Methods. International Conference on Molecular Electronic Structure. 28th–31th May 2018 Metz, France. Talk.
