"I am Winston Wolf, I solve problems" - Q. Tarantino

Modélisation des Systèmes Complexes

Le groupe de Chimie Théorique et Modélisation dirigé par le Pr. Carlo ADAMO est installé au sein de l'Institut de Recherche Chimie Paris (IRCP), dans les locaux de l'École Nationale Supérieure de Chimie de Paris (ENSCP).

CECAM : Charge Transfer Modeling in Chemistry

Posté le 27 mars 2015

New methods and solutions for a long-standing problem

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: Electronic Structure Methods, Chemical environment and Applications in Chemistry.

ENSCP, Amphi Moissan

du 7 au 10 Avril 2015

Séminaire du Pr. Orazio Nicolotti

Posté le 7 septembre 2014

REACH and QSAR : chimera or opportunity ?

REACH is indeed the most ambitious chemical legislation in the world. Companies must report (eco)toxicological information about their chemicals, disseminated to the public domain by the European Chemicals Agency after their registration. The availability of this wealth of new toxicological data, together with the promotion of REACH of in silico methods, has given to Quantitative Structure Activity Relationships (QSARs) a key role for regulatory purposes. REACH has in fact refreshed the (Q)SAR potential and renewed its main aim that is the prediction of a number of relevant endpoints necessary for the registration and, more importantly, marketing of chemicals following the REACH motto “no data no market”. A number of examples will be presented to provide an enlightened appraisal of this attractive new opportunity.

ENSCP, salle 4.

le 16 Septembre à 11h.

Séminaire du Dr. Gianluca Lattanzi

Posté le 7 septembre 2014

MD Simulations of organic polymers employed in Organic Thin Film Transistors (OTFT)

Organic thin film transistors (OTFT) are metal−insulator−semiconductor field-effect transistors in which the semiconductor is a conjugated organic material. They are currently employed in several devices that may act as sensors of organic molecules, for a number of industrial/medical applications. Despite the large amount of experimental efforts in the characterization of the electronic properties of these devices, several questions regarding their morphological arrangement in bulk and at interfaces remain wide open. I will report our recent results obtained by classical molecular dynamics simulations of the semiconductor polymers P3HT and PBTTT inspired by OTFT fabrication techniques, discuss how we are currently addressing the problems posed by the interaction of organic polymers with the functionalized substrates and introduce novel applications of these materials that involve also the interaction with biological macromolecules.

ENSCP, amphi Chaudron.

le 15 Septembre à 11h.

14ème Rencontre des Chimistes Théoriciens Francophones

Posté le 5 juin 2014

Comité organisateur : C. Adamo, J. Contreras Garcia, I. Demachy, C. Léonard, A. Perrier-Pineau, A. Markovits, F. Maurel et P. Reinhardt. Plus d'informations sur le site dédié du RCTF : http://rctf2014.sciencesconf.org/

ENSCP, amphi Friedel.

du 30 juin au 4 juillet 2014.

Séminaire du Dr Michael Wykes

Posté le 18 avril 2014

Computational Engineering of low band copolymers

Reliable prediction of the colour of organic dyes for screening and material-design purposes places severe accuracy requirements on the method being used. While such accuracy is perhaps achievable for small molecules using highly correlated wavefunction-based methods and large basis sets, their high computational cost prohibits routine application to large molecules and polymers, which these days are mainly treated with DFT and its TD extension. Here we use popular hybrid and long-range corrected functionals to predict the optical bandgaps of several low-bandgap polymers used in organic solar cells by extrapolating from the bandgaps of series of oligomers. By carefully comparing to experimental studies of homo- and co-oligomer series, we find that B3LYP, CAM-B3LYP, IP-tuned LC-BLYP and BHLYP all significantly overestimate changes in bandgap as a function of system size, while M06HF, which uses 100% HF exchange, provides excellent agreement with experiment. Following an empirical offset-correction to account for strongly overestimated transition energies, TD-M06HF bandgaps are within ~0.1 eV of measured values, suggesting that this approach could provide useful predictions of related low-bandgap oligomers and polymers for screening and material-design purposes.

ENSCP, salle 3.

Le 24 avril à 14h30.

Séminaire du Pr Juan Carlos Sancho-Garcia

Posté le 21 avril 2014

Recent applications of double-hybrid density functionals

Double-hybrid density functionals have recently entering into the field of computational chemistry, thanks to the combination of high accuracy together with greater robustness and reliability than the widely employed hybrid functionals. They are all rooted on the adiabatic connection method but, as well as for corresponding hybrid functionals, two families can be found, be they parameterized or not. We present recent achievements concerning applications to chemical systems of the most interest, and current extensions to deal with challenging issues such as non-covalent interaction and excitation energies. The use of a double-hybrid density functional, i.e. B2-PLYP vs B3LYP or PBE0-DH vs PBE0, is found to always improves the description of any of the tackled systems.

ENSCP, salle 3.

Le 23 avril à 14h30.

Séminaire du Dr Francesco Giannici

Posté le 10 mars 2014

Functionalization of a layered oxide with organic moieties: towards hybrid proton conductors

The design of innovative proton conductors for intermediate-temperature fuel cells, closing the gap between PEMFC and SOFC, is a forefront research theme in materials chemistry. Layered perovskites with the Dion-Jacobson structure (ALaNb2O7) have bidimensional lanthanum niobate sheets, separated by a layer of A+ variety of molecules with soft chemistry, to yield inorganic-organic hybrids. In particular, the intercalation of amines, alcohols, carboxylic or phosphonic acids, and their covalent binding to the sheets has been demonstrated recently. We present here our first results on the intercalation and covalent bonding of different organic molecules: as a first step, smaller molecules (such as alcohols) are intercalated to expand the interlayer space, then the proton carriers (such as imidazoles or sulfonates) are bound to the surface. The intercalation process is investigated by XRD (to measure the interlayer distance) and TGA (to determine the weight loss upon thermal decomposition). NMR is applied to confirm the covalent bonding between the organic and oxide parts. The intercalation behavior of different functional groups is explained in terms of van der Waals and/or hydrogen bonding between organic chains, and the requirements for the layer-by-layer deposition of the powders are discussed.

ENSCP, salle 4.

Le 20 mars à 15h30.

Séminaire du Dr Art Cho

Posté le 3 novembre 2013

Applications of Density Functional Theory in Computational Drug Discover

Density functional theory (DFT) has been successfully applied to many fields for its efficiency and versatility. Materials science and quantum chemistry are examples of those fields in which DFT methods are inseparable in current research. On the other hand, it has been rare to utilize DFT for biological problems until recently. Computational drug discovery, in which protein docking is the central methodology, is one such field. This is due to 2 main reasons: 1. biomolecules are large compared to other chemical molecules and therefore it would be prohibitively time-consuming to run DFT calculations on the whole systems, and 2. most interactions within biomolecular systems are non-quantum in nature. However, it turns out that there are cases in computational drug discovery, for which molecular mechanical level description is not enough. For this reason, we have developed a series of methods incorporating DFT calculations for computational drug discovery, which proved to be effective for a number of different classes of problems. Versatility of DFT should be tamed in application of it to various problems. Different flavors of DFT have different performances. There is still quite a lot of room to improve in terms of finding the right functional for computation drug discovery application of DFT. In this talk, I will describe our previous efforts in development of protein docking methods using DFT calculations and the results of our recent collaboration with Professor Cortona group in applying the newly developed DFT functional to computational drug discovery problems.

ENSCP, salle 2.

Le 15 novembre à 15h30.

Séminaire du Dr Giuseppe Milano

Posté le 5 septembre 2013

Hybrid Particle-Field Theoretic Molecular Dynamics Simulations

This recent hybrid particle-field technique combines molecular dynamics (MD) and self consistent field theory (SCF).The main feature of the hybrid MD-SCF method is that the evaluation of the nonbonded forces between particle pairs is replaced by an evaluation of an external potential dependent on the local density. This framework allows to develop coarse-grained models with chemical specificity but at the same time, using an efficient parallelization scheme, opens the possibility to simulate large-scale systems. The basic methodology and the theory will be presented and several applications (ranging from biomembranes, to drug delivery and polymer composites) will be described.

ENSCP, salle 4.

Le 20 septembre à 15h00.

Séminaire du Dr Thierry Tron

Posté le 8 mai 2013

Visible Light-Driven dioxygene Reduction by Sensitizer-Laccase System

Laccases are very well known biocatalysts with great robustness, high oxidation power and substrate versatility (among other properties). They contain a unique set of copper ions made of one each of the three types of biorelevant copper sites: type 1 (T1), type 2 (T2) and a binuclear type 3 (T3), and couple dioxygen reduction to the oxidation of substrates, either organic or metal ion. They belong to the Blue Copper Binding Domain (BCBD) family of proteins in which the archetypal members are the plant or bacterial electron transfer protein cupredoxins (CUP). In this family, function is modulated by the number of CUP domains, the number and type copper atoms and the fusion to non metalled domains. Taking natural plasticity within the BCBD family as a source of inspiration for the engineering of laccases, we aim at shaping new catalysts based on a laccase platform functionalized with “plug-ins”. One of our targets is to develop a robust system where light absorption triggers electron transfer from a catalytic centre to a renewable electron acceptor. We report here on the light driven four-electron reduction of a laccase that ultimately converts dioxygen into water using ruthenium(II) polypyridine or porphyrin type chromophores and a sacrificial electron donor. Prospects of creating renewable aerobic photo oxygenation catalysts will be discussed.

ENSCP, amphi Moissan.

Le 15 mai à 15h00.

Séminaire du Pr Nadia Rega

Posté le 30 janvier 2013

Computational photochemistry for molecular recognition.

We present a summary of our ongoing research in computational photo-reactivity and spectroscopy, including steady-state and time resolved optical spectroscopy. Our computational tools are mainly rooted in time-dependent density functional theory, hybrid quantum mechanical/molecular mechanics methods, and ab-initio dynamics with non periodic boundary conditions. As study cases, we illustrate our recent results elucidating the solvation dynamics of the 6-N-methyl-quinolone solvatochromic dye, and some aspects of the green fluorescent protein photochemistry.

ENSCP, salle 4.

Le 31 janvier à 11h00.

Séminaire du Dr Corentin Boilleau

Posté le 14 décembre 2012

Ab initio study of magnetic properties from mono and multi determinantal methods

The multidisciplinary interest in magnetic systems stems from the many technological applications in which they are involved, ranging from spintronics (as sensing, memory, or switching devices) to soft matter (as contrast agents for magnetic resonance imaging, spin labels, or mediators for controlled radical polymerization). This work is focused on the theoretical study of their properties. The main characteristics of magnetic systems reside in their intrinsic multireference character that comes from the existence of weakly coupled unpaired electrons. Their theoretical study requires highly correlated treatments and the modelization of their properties usually relies on model Hamiltonians. Ab initio calculations may help to understand the microscopic origin of their macroscopic properties and are often used to evaluate quantitatively the interactions of these model Hamiltonians. The first part of this work concerns the extraction of model Hamiltonian interactions from WFT and DFT calculations. Extractions of Hubbard, Heisenberg, double exchange and Ising Hamiltonians are performed on magnetic spin s=1 systems, mixed valence systems and organic diradicals. The second part deal with the study of iron(II) complexes and their energetic spectra, a fundamental step to determine relaxation process in LIESST compounds (Light Induced Excited Spin State Trapping). Currently, important efforts are made to predict microscopic electronic mechanisms involved in photo-induced spin transitions, but difficulties are still encountered concerning the physics of the excited states. Initially, a study rationalizes the correlation between the structural parameters of these compounds and their LIESST temperature. And finally, a theoretical approach through DFT, TDDFT and WFT calculations is proposed in order to highlight different decay channels.

ENSCP, salle 2.

Le 17 décembre à 14h00.

Séminaire du Dr Aurélie Perrier

Posté le 26 novembre 2012

Modélisation de la réactivité et des propriétés optiques de molécules photochromes au sein de systèmes complexes.

Les molécules photochromes organiques présentent des potentialités indéniables quant à leur utilisation dans la transmission et le stockage de l’information par voie optique ou électronique. Pour les interrupteurs moléculaires de type dithiényléthène (DE), la commutation repose sur une réaction réversible induite photochimiquement entre deux états, ouvert et fermé, possédant deux spectres d’absorption différents. La synthèse de multi-photochromes constitue aujourd’hui un axe de recherche particulièrement actif, l’objectif étant de concevoir des opérateurs logiques permettant d’accéder à un plus grand nombre d'états. Ainsi, pour un composé formé par deux DE, des réactions d’isomérisation successives peuvent avoir lieu entre trois états différents. Toutefois, des études expérimentales récentes ont montré que, selon la nature du lien reliant les deux unités photochromes, la forme totalement fermée pouvait ne pas être détectée. A l’aide de calculs basés sur la Théorie de la Fonctionnelle de la densité (DFT) et de la TD-DFT, nous avons étudié une série de composés bi- puis tri-photochromes. Une analyse orbitalaire, outil à la fois simple et puissant, nous a permis d’évaluer le couplage entre les différentes unités photochromes et d’aider à la conception de dimères totalement photoactifs. Nous avons également appliqué cette méthodologie à l’étude de la photoréactivité de molécules photochromes greffées sur des nanoparticules métalliques.

ENSCP, amphithéâtre Moissan.

Le 27 novembre à 14h00.

Séminaire du Pr Matthias Ernzerhof

Posté le 05 novembre 2012

Kekulé formulas, orbitals of graphene, and electron transport

Zero-dimensional graphenes, also called nano-graphenes (NGs), consist of fragments of graphene with a finite number of hexagons. NGs can be viewed as a subset of the polycyclic aromatic hydrocarbons (PAHs) that continue to attract chemists’ attention. We develop a simple theory for the electron transport through NGs which combines elements of the electronic structure theory of graphene, intuitive methods for the calculation of the molecular conductance, and chemical concepts such as Kekulé structures. This theory enables one to analyze the relation between the structure of NGs and their conductance. In the second part of the talk, we address the problem of metastable states. These stated describe for instance molecules attached to surfaces that emit electrons into the bulk. We present the recently developed complex-density functional theory (CODFT), which extends the Kohn-Sham method to the realm of metastable states.

ENSCP, amphithéâtre Friedel.

Le 05 novembre à 15h30.

Séminaire du Dr Sylvestre Bonnet

Posté le 15 octobre 2012

Coordination-and Photo-chemistry at lipid bilayers

My group focuses on studying the coordination chemistry and photochemistry of transition metal ions at lipid bilayers. Two systems recently studied in Leiden will be described that highlight the importance of electrostatic interactions between positively charged metal complexes and negatively charged biomimetic membranes. In the first system, a monodentate thioether ligand is embedded in the lipid bilayer and a large ruthenium(II) complex is introduced in the solution. In the dark and at room temperature a Ru-S coordination bond forms spontaneously at the water- bilayer interface. Upon visible light irradiation this Ru-S bond is selectively broken, releasing the aqua complex in the vicinity of the bilayer that can further bind to another thioether ligand. Thus, the Ru complexes “hop” repeatedly at the membrane-water interface under the influence of visible light. In the second example a tetrapyridyl ligand is embedded in the membrane, which can bind to small zinc(II) ions present in the solution. Upon binding the fluorescence of the ligand is significantly increased, thus opening the route towards zinc sensing in biological systems. Although these two cases are very different in both cases the binding of the metal ion to the membrane-embedded ligand only takes place with negatively charged membranes. We will discuss the implication of these results for coordination chemistry and for the modeling of ligand-metal interactions in biomimetic media.

ENSCP, salle 4.

Le 16 octobre à 11h00.