[The school will take place online]

Photoinitiated processes are not only important for understanding natural phenomena but they also play an undeniable role in the booming fields of renewable energy, material design and medicine. Excited-state processes have traditionally been explained from a static point of view, delivering in some cases a biased, incorrect or even incomplete description of the former. The simulation of the dynamics of such processes is therefore fundamental for the quest to understand the chemical and physical mechanisms.

The purpose of this school is to introduce its participants to state-of-the-art methodologies for the simulation of the dynamics of processes in the excited state, following the evolution in time of photoinitiated reactions, one of the priority topics of this call.

Motivation

In detail, the motivation of the school is to provide the attendants with the basic tools and knowledge to be able to simulate photoinduced processes, from conventional electronic spectroscopy to ultrafast laser-triggered phenomena, and especially covering photochemical reactivity. The approach to such simulations is carried out by ab initio strategies, including static calculations using multiconfigurational methods (electronic ab initio methods,) and dynamics simulations using different approaches for the treatment of the nuclei, from full quantum dynamics to mixed quantum-classical dynamics.

On one hand, these types of calculations are essential for characterizing excited states, i.e. any photophysical and photochemical process initiated by light absorption in molecular systems, and its time evolution. The importance of such processes covers areas from biology/medicine to physical/material science and energy conversion. For instance, the interaction between UV light and DNA is the main source of direct DNA-photodamage but has also been applied in novel phototherapies against cancer and virus treatments. In this context, the use of computational methods explicitly suited to treat electronic excitation and its time evolution in biologically relevant molecules, provides a complementary picture that gives insight in such processes. Furthermore, the development of new nanomaterials profiting of efficient and reversible photochemical reactions (photoswitches, microreactors) as well as the understanding of ultrafast (femto to attosecond) charge migration in ionized systems have grown exponentially in the last decades. Finally, photoinduced processes are at the heart of the conversion of sunlight into energy, and the detailed understanding of such phenomena will enable the development of more efficient technologies for clean energy production.

On the other, many other fundamental ground state processes as dissociation, ionization or triplet state formation (reactions that take place in the atmosphere and in the interstellar space), usually involves competing mechanisms described by open-shell electronic states and requires also the use of this kind of computational tools.

At the end of the school the students will be able to apply the acquired abilities to their own research project covering any of the above-mentioned subjects and others related with electronic and vibrationally excited states in complex molecular systems.

Students

The school will be carried out in the frame of the Master in Theoretical Chemistry and Computational Modeling (TCCM) that has been recently supported by the Erasmus+ Programme of the European Union. This programme provides scholarships for worldwide students that will attend the school as training course during their first year of master studies after several intensive courses.

The school is also oriented and open to other postgraduate students in other areas such as atomic and molecular physics and in higher research levels (PhD students, postdocs or early-stage researchers) initiating in these types of computations.

Only basics in quantum chemistry are required as previous knowledge to attend the school since we provide also introductory lessons to photochemistry. In particular: Hartree-Fock Theory, Basis Sets, and basics on Configuration Interaction theory and Born-Oppenheimer approximation.

Goals

The attendants at the end of the school would be able to:

1. Understand the main process taking place after light absorption by a molecule: radiative (fluorescence, phosphorescence) and non-radiative (internal conversion, intersystem crossing, photochemistry…) and their competition.
2. Perform multiconfigurational (CASSCF/CASPT2) and TD-DFT calculations for excited states: simulation of vibrationally resolved electronic absorption spectra and characterization of potential energy surfaces.
3. Set up and run dynamics simulations: pump-probe spectroscopy and non-adiabatic dynamics. 
4. Use several commercial and non-commercial computational packages and codes (OpenMolcas, FCclasses, Octopus, Newton-X).

The achievement of these main objectives is ensured due to the organization of the school, i.e. theoretical lessons delivered by internationally recognized experts in the field, complemented with computer sessions and designed in 3 interrelated blocks, which gradually build up the necessary knowledge, starting from the basics to eventually provide the students with state-of-the-art simulation methods for photochemistry. Six lessons provide the basis for the theoretical concepts that are settled and applied during 6 practical sessions in which the students perform the simulations by their own guided at every moment by the teachers.