Charge Transfer Modeling in Chemistry: new methods and solutions for a long-standing problem
- Masahiro Ehara (Institute for Molecular Science, Japan)
- Rika Kobayashi (Australian National University, Australia)
- carlo adamo (Ecole Nationale Superieure de Chimie de Paris, France)
- Ilaria Ciofini (CNRS, France)
The aim of the workshop is to bring together different theoretical and computational scientists all working in the field of charge transfer (CT) phenomena in chemistry. These persons will bring all the different facets of CT, which are normally developed within different communities and often applied to very different fields. Three core aspects will be analyzed and discussed within the workshop:
1) Electronic Structure Methods
• DFT-based methods are appealing for their valuable accuracy/computation-cost ratio but clearly show limitations theoretically (correctly modelling exchange-correlation contributions and long-range behaviour) and practically (accurate descriptions of real phenomena). These limitations can be addressed by the invited DFT developers and applications specialists. Also, DFT descriptors developed to assess the quality of the TD-DFT results and thus to gain insights on the chemistry and physics of CT phenomena, will be discussed.
• WF-based methods are often necessary to reach high accuracy or, more simply, as references for approximate TD-DFT approaches. However, currently existing high-accuracy methods are too expensive to tackle many problem sizes of interest. Current developments in WF-based will be discussed especially focusing on recent numerical developments which make these methods competitive with TD-DFT.
• Recent advances in Many Body Perturbation Theory for the description of excited state CT phenomena will be discussed as a suitable alternative to both post-HF and TD-DFT methods
2) Chemical environment
• Electronic states with a charge separation are strongly affected by the close chemical environment, either by simple energy stabilization or by more complex phenomena. This is particularly relevant for real systems of interest where the influence of a solvent or the larger environment of a protein or enzyme, is important. The different levels, depending on the nature and action of the environment, at which these effects can be treated, such as simple yet effective solvent models, like PCM, or more detailed approaches such as QM/QM’, eventually including electronic embedding (QM/QM’ + EE), will be discussed by key developers in the field.
3) Applications in Chemistry
• Biological systems – CT plays a fundamental role in many biological processes, such as enabling vision via retinal or photosynthesis in chlorophylls. Understanding these processes is still an important area in the crop industry for improving yields. Amongst our invited speakers we have method developers who have also extensively studied these systems to evaluate their methodology. Other biological application specialists can bring to the attention of the developers further problems in existing methods.
• Molecular devices have become a key area in next-generation technology with applications such as optical data storage, optical switching and logic gates. The movement of electrons is a fundamental part in their mechanism and a better understanding will aid in better design. Again, experts in such applications, especially in the conception of push-pull systems, can highlight existing problems.
1. "The application of CAM-B3LYP to the charge-transfer band problem of the zincbacteriochlorin-bacteriochlorin complex" R. Kobayashi and R. D. Amos Chem. Phys. Letters 420, (2006) 106 .
2. "Assignment of the Q-Bands of the Chlorophylls: Coherence Loss via Qx-Qy Mixing" J. R. Reimers, Z.-L. Cai, R. Kobayashi, M. Rätsep, A. Freiberg and E. Krausz Scientific Reports, 3, Article number: 2761 2013/09/26/online | oi:10.1038/srep02761
3. TD-DFT Assessment of Functionals for Optical 0-0 Transitions in Solvated Dyes
D. Jacquemin, A. Planchat, C. Adamo and B. Mennucci J. Chem. Theory Comput. 8 (2012) 2359-2372.
4. Rhodopsin Absorption from First Principles: Bypassing Common Pitfalls O. Valsso,. P. Campomanes, I. Tavernelli, U. Rothlisberger and C. Filippi J. Chem. Theory Comput. 9 (2013) 2441-2454.
5. Symmetry-adapted cluster and symmetry-adapted cluster-configuration interaction method in the polarizable continuum model: Theory of the solvent effect on the electronic excitation of molecules in solution R. Cammi, R. Fukuda, M. Ehara and H. Nakatsuji J. Chem. Phys. 133 (2010) 024104.
6. Chemically intuitive indices for charge-transfer excitation based on SAC-CI and TD-DFT calculations. M. Ehara, R. Fukuda, C. Adamo and I. Ciofini J. Comp. Chem., 34 (2013) 24982501.