Project

Discipline

First-principles excited state dynamics; Density functional theory; Photo-induced water splitting; Spin-orbit couplings and intersystem crossing; OLED technology; Photo-induced drug delivery; Nuclear quantum (de-)coherence and dephasing; Time dependent density functional theory; Energy production; Cancer therapy; Nonadiabatic dynamics

Lead
Interaction entre la lumière et la matière à partir de principes premiers: nouveaux développements en dynamique non-adiabatique avec applications à l'énergie (production, économie et stockage) et à la recherche médicale.
Lay summary
L'objectif principal de ce projet est d'améliorer et de dériver des nouveaux moyens théoriques, basés sur les principes premiers de la mécanique quantique, pour l'étude de l'interaction entre la lumière (notamment les radiations solaires) et des dispositifs moléculaires ou à l'état solide pouvant être utilisés pour la production et le stockage d'énergie . Nous avons récemment montré que des calculs de structure électronique pour l'obtention de propriétés de l'état fondamental et d'états excités, basés sur la théorie de la fonctionnelle de la densité (DFT) et la théorie de la fonctionnelle de la densité dépendante du temps (TDDFT), peuvent être combinés à des méthodes de dynamique moléculaire (MD) non-adiabatique afin de décrire divers phénomènes photophysiques et photochimiques en solution ou à l'état solide. Dans la première partie de ce projet nous visons à développer d'avantage notre méthode de MD avec des trajectoires avec sauts de surface (TSH), basée sur la TDDFT, qui atteint un bon équilibre entre la précision et l'efficacité numérique. Tous les logiciels développés seront mis à disposition de la communauté scientifique gratuitement, sur le site www.cpmd.org. En plus du développement théorique décrit précédemment, le projet comporte aussi un partie d'application de la théorie à deux problèmes majeurs liés à la conversion d'énergie solaire et à l'économie d'énergie. En premier lieu nous allons nous intéresser à la conception de nouveaux dispositifs pour le craquage de l'eau, et en particulier au « design » de catalyseurs pour la production d'hydrogène à partir de l'énergie solaire. Nous allons aussi nous intéresser au développement de technologies d'éclairage plus efficaces basées sur les diodes électroluminescentes organiques (OLEDs), notamment ceux basés sur les complexes d'iridium, dont nous visons à optimiser le spectre d'absorption et émission (« spectral tuning »).

Direct link to Lay Summary

Last update: 08.04.2013

Active participation

Active participation

The principal aim of this project is to improve on and to derive new theoretical first-principles techniques for the investigation of the interaction of light (and in particular the solar radiation) with molecular and solid state devices that can be used for energy production and conversion, or that can replace old, energy inefficient apparatus. Recently, we showed that density functional theory (DFT) and time-dependent DFT (TDDFT) based electronic structure calculations for ground and excited state properties combined with suitable nonadiabatic molecular dynamics (MD) schemes offer an adequate description of many types of photochemical and photophysical processes in both solution and the solid phase. Therefore, in the first part of this project we plan to further develop our recently proposed TDDFT-based trajectory surface (TSH) molecular dynamics (MD) scheme [1], which offers an advantageous balance of accuracy and numerical efficiency. Among others, the main developments include: (i) a theory for the calculation of spin-orbit couplings in the framework od DFT and TDDFT, (ii) the implementation of more accurate DFT functionals and TDDFT kernels, and (iii) the design of a model for the coupling of the electronic and quantum nuclear degrees of freedom with the environment that goes beyond the classical QM/MM scheme and that therefore allows the study of phenomena like quantum dephasing and entanglement. Furthermore, in order to improve the description of the nuclear quantum effects within this formalism, we propose a new theoretical development based on quantum hydrodynamics (or quantum Bohmian dynamics), which introduces quantum (de-)coherence between the ‘quantum’ trajectories used to propagate the nuclear wavefunction. Starting from our recent development in reference [2], we plan to extend our TDDFT-based nonadiabatic Bohmian dynamics MD scheme to treat realistic systems of the size and complexity that are relevant for the applications addressed in this proposal. All this theoretical and software development will be made available to the scientific community, free of charge, from the address: www.cpmd.org [3].In parallel to the theoretical development, we will also address two main problems related to solar energy conversion and energy-saving, namely the design of improved light-induced water splitting devices and development of more efficient illumination technologies based on organic light-emitting-diodes (OLED). Instead of the direct conversion of solar energy into electric power (by means of a solar cell device), it was proposed to store this energy in chemical form, for instance, with the production of molecular hydrogen (H2). The simplest way to achieve such an energy conversion is by splitting water using solar radiation. To run this process efficiently, robust water oxidation catalysts are required to produce oxygen efficiently, that is, with high rates and using only a small (or better no) over-potential. The design of better catalysts is therefore key to the development of this technology and the use of adequate and predictive theoretical methods (like the ones developed in this proposal) is of enormous importance. Concerning energy-saving, our aim is to improve and design new kinds of OLEDs (mainly based on iridium dopants, but not exclusively) with desired absorption and emission properties and protection against photodegradation. By means of a theoretical investigation it is possible to optimally tune the absorption spectrum of a compound by selective mutation of the ligands attached to the central metal (spectral tuning). In conjunction with nonadiabatic MD it will be possible to shed lights on the excited state dynamics identifying for instance, intersystem crossings (via spin-orbit coupling), and also to locate potential energy minima on the excited PESs from which the OLED is emitting. Finally, we believe that the advanced theoretical tools we have developed so far will allow us to address, with new insights, another major challenge facing our society in the domain of public health: cancer therapy. The purpose of this study is the design of a new class of anti-cancer drugs based upon the combination of nanoparticles with light-induced drug delivery. Nanoparticle accumulate in tumor tissue thanks to the defective angiogenesis of cancer tissues. Combining this efficient drug delivery vector with a cytotoxic drug that can be released upon irradiation with tunable light (in the UV of X-ray range) it is possible to obtain a new powerful nano-technological device that can selectively kill tumors. [1] E. Tapavicza, I. Tavernelli, and U. Rothlisberger, “Trajectory surface hopping within linear response time-dependent density-functional theory”, Phys. Rev. Lett. , 98, 023001 (2007).[2] I. Tavernelli, “Ab initio-driven trajectory-based quantum dynamics in phase space”, submitted to Phys. Rev. A, June 2012.[3] CPMD, http://www.cpmd.org. Copyright IBM Corp. 1990-2008, ?Copyright MPI für Festkörperforschung Stuttgart 1997-2001.