Theory Department
Director: Angel Rubio
The electronic and structural properties of advanced materials, nanostructures and molecular complexes are the focus of the Theory Department's work. Researchers focus on developing novel theoretical tools and computational codes to investigate and control the electronic response of such systems to arbitrary time-dependent external electromagnetic (quantum) fields. We aim to provide a detailed, efficient, and at the same time accurate microscopic approach for the ab-initio description and control of the dynamics of decoherence and dissipation in quantum many-body systems. We seek to characterize new non-equilibrium states of matter.
Several independent research groups are exploring different approaches and applications including theory of ultrafast phenomena in molecular and condensed matter phases, time-dependent-functional theory for quantum-electrodynamics, non-equlibrium phenomena and new states of matter, time-resolved spectroscopies, theoretical spectroscopy and XFEL/CFEL studies of molecules and solids, strong light-matter interactions and optimal control theory and applications to two-dimensional and correlated materials, nanostructures and biomolecules for energy applications.
The paper 'Wavefunction embedding for molecular polaritons' by Fabijan Pavošević and Ángel Rubio has been selected for the cover of the Journal of Chemical Physics. (
https://doi.org/10.1063/5.0095552)
ABSTRACT
Polaritonic chemistry relies on the strong light–matter interaction phenomena for altering the chemical reaction rates inside optical cavities. To explain and understand these processes, the development of reliable theoretical models is essential. While computationally efficient quantum electrodynamics self-consistent field (QED-SCF) methods, such as quantum electrodynamics density functional theory, need accurate functionals, quantum electrodynamics coupled cluster (QED-CC) methods provide a systematic increase in accuracy but at much greater cost. To overcome this computational bottleneck, herein we introduce and develop the QED-CC-in-QED-SCF projection-based embedding method that inherits all the favorable properties from the two worlds: computational efficiency and accuracy. The performance of the embedding method is assessed by studying some prototypical but relevant reactions, such as methyl transfer reaction, proton transfer reaction, and protonation reaction, in a complex environment. The results obtained with the new embedding method are in excellent agreement with more expensive QED-CC results. The analysis performed on these reactions indicates that the electron–photon correlation effects are local in nature and that only a small region should be treated at the QED-CC level for capturing important effects due to cavity. This work sets the stage for future developments of polaritonic quantum chemistry methods and will serve as a guideline for the development of other polaritonic embedding models.
