Robert Benda

PhD student : Multi-scale modeling of water quality nanosensors based on carbon nanotubes and conjugated polymers.

Expertise : Molecular simulations and modeling (from quantum electronic methods to atomistic force fields), model parametrization and model reduction, scientific codes use and development.

Supervisors : Eric Cancès (CERMICS, ENPC), Bérengère Lebental (LPICM, IFSTTAR)

Institutions : CERMICS, Ecole Nationale des Ponts et Chaussées and LPICM, Ecole Polytechnique.

Publications :

  • Link to Google Scholar list of publications.
  • Current project (water quality monitoring) :
  • Robert Benda, Thomas Vezin, Eric Cancès, Gaël Zucchi and Bérengère Lebental, Prediction of the interaction strength of an urea-based probe towards
    ions in water by means of DFT/PCM calculations    , to be submitted.
  • Robert Benda, Gaël Zucchi, Eric Cancès, and Bérengère Lebental, Insights into the π−π interaction driven non-covalent functionalization of carbon nanotubes of various diameters by conjugated fluorene and carbazole copolymers , Journal of Chemical Physics 152, 064708 (2020). Link to the paper.
  • Robert Benda, Eric Cancès and Bérengère Lebental, Effective resistance of random percolating networks of stick nanowires: Functional dependence on elementary physical parameters , Journal of Applied Physics 126, 044306 (2019). Link to the paper.
  • Bérengère Lebental, Robert Benda, Laurence Bodelot, Ileana Florea, Mallesham Godumala, Boris Gusarov, Alfredo Gutierrez, Loic Loisel, Erick Merliot, Sasikumar Ramachandran, Xin Yang Zhang, Gaël Zucchi, Carbon nanotube sensor array for water monitoring with conjugated polymers , C’NANO 2017, The Nanoscience Meeting, Dec 2017, Lyon. Link .
  • Former projects (Hall effect and geometry, non-equilibrium thermodynamics) :
  • Robert Benda, J.M. Rubi, E. Olive and J.-E. Wegrowe, Towards Joule heating optimization in Hall devices, Physical Review B 98, 085417 (2018). Link to the paper.
  • J.-E. Wegrowe, R. V. Benda and J. M. Rubí, Conditions for the generation of spin and charge currents in bulk spin Hall devices, Europhysics Letters, 118 6 (2017) 67005. Link to the paper.
  • Jean-Eric Wegrowe, Robert Benda, Miguel Rubi, Conditions for the existence of spin to charge current conversion in spin-Hall devices: the Hall bar versus the Corbino disk (Conference Presentation), Proceedings Volume 10357, Spintronics X, 103570A (2017). Link .

Reviewer for the following journals :

  • Journal of Applied Physics (August 2020).

Seminars :

  • Informal Scientific Discussion (ISD) seminar of LSI laboratory, Ecole Polytechnique, Palaiseau, March 2019. Link to the presentation.
  • Machine Learning seminar, CERMICS laboratory (November 2019). Link to the presentation.
  • Journées IPEF 2020, Agro ParisTech. Link to the presentation.

Poster presentation :

  • Journées Théorie, Modélisation et Simulations, IPBC (June 2019).
  • Poster presented at GDR Graphene, Graphene & Co Meeting 2019, Bad Herrenalb, Germany, October 2019.
  • Journées des thèses IPEF (January 2021). Link to the poster.

Attended workshops :

  • Mini-school on mathematics for theoretical chemistry and physics (GDR NBODY), June 2019.

Research :

  • Mesoscopic scale : Modeling of random percolating networks of nanowires (graph theory, resistor networks), towards computer assisted carbon nanotubes networks design . Understanding of the different contributions to the response of carbon nanotube networks used as a sensing device (see this paper ).
  • Nanoscopic scale : Modeling and simulation of the non-covalent functionalization of (Single Wall up to Multi Wall) carbon nanotubes by one or several conjugated polymers : molecular dynamics simulations with classical or reactive force fields (see this paper ). Computed assisted polymer design (in a sensing perspective) : backbone and side-chain fine-tuning, nanotube diameter fine-tuning.
  • Nanoscopic scale : Understanding of the weak pi-pi interaction between aromatic molecules and graphene-like surfaces (role of dispersion forces, level of theory needed to capture the energy barrier between the ‘stacked’ and ‘sandwich’ configuration) and ‘charge transfer’ from the molecule to graphene or carbon nanotube surface (see this presentation).
  • Nanoscopic scale : Modeling and understanding of the complexation of target ions (chlorine, nitrate, phosphate, hypochlorite, heavy metals, etc.) by specific functional groups, at different levels of theory (classical force field, polarizable force field, ab-initio simulations) either with implicit or explicit solvation models (free energy computations). Study of entropic effects, binding affinites, competitive active sites and influence of interfering ions. Computer assisted probe design (in a sensing perspective).
  • Nanoscopic scale : Electronic transport in carbon nanotubes and graphene-like materials. Origin of the room temperature resistance in graphene and carbon nanotubes. Influence of Coulomb impurities, phonons, defects (such as adsorbed ions) or doping on transport properties, in a sensing perspective.
  • Model parametrization : Force field parametrization (fixed-charge and polarizable force fields).
  • Methodological improvements : Distributed Multipole Analysis (DMA) and Iterative Stockholder Analysis partitioning (ISA) for the parametrization of polarizable force fields.
  • Methodological improvements : Direct minimization methods to solve the density self-consistent cycle (SCF) convergence problems for open-shell heavy metal ions (Restricted Open-Shell Hartree-Fock).
  • Methodological improvements : Optimization of implicit solvation models (PCM) parameters to improve the accordance with the results of explicit solvation models.

    • Fields of expertise

    • Computational chemistry (wave function theory methods, DFT, classical semi-empirical force fields, polarizable force fields).
    • Force fields parametrization methods (parameter generation and optimization).
    • Implicit solvation models.
    • Model reduction.
    • Scientific computing and code development.
    • Former research : non-equilibrium thermodynamics and Hall effect (influence of the geometry of the device on the stationary states, use of conformal transformations).

    Simulation codes and softwares

    • Molecular dynamics codes :
    • LAMMPS (in particular ReaxFF force field).
    • GROMACS (and automatic parametrization tool ATB) .
    • Tinker, Tinker HP.
    • Quantum chemistry codes (for molecules) :
    • GAMESS (structural minimizations in vacuo or implicit solvent, vibrational analysis)
    • Psi4
    • Gaussian
    • CP2K
    • Quantum Package (programming environment to design new algorithms in quantum chemistry)
    • Plane-wave periodic quantum codes and post-treatment :
    • Quantum Espresso (carbon nanotubes model systems)
    • Wannier90 (conductivity of carbon nanotubes + ions model systems)
    • DFTK
    • Local multipole moments computation (for polarizable force fields parametrization) :
    • GDMA (Distributed Multipole Analysis)
    • Horton (Iterative Stockholder Analysis partitioning)
    • Polarizable force field parametrization and optimization (AMOEBA) :
    • Poltype (generation of AMOEBA parameters for a new molecule)
    • Force Balance (force field parameter optimization, e.g. AMOEBA)
    • Visualization softwares :
    • SAMSON (high throughput construction, visualization of molecular systems, simulations with simple force fields, etc.)
    • VMD (molecular dynamics trajectories)
    • Avogadro (visualization of electronic orbitals)
    • Other libraries, softwares or coding languages :
    • Open Babel
    • Python
    • Julia
    • Fortran

    Code development

    • Monte-Carlo simulations for random nanowire networks effective resistance computation (Python).
    • More flexible code for Distributed Multipole Analysis (Python).
    • More flexible code for Iterative Stockholder Analysis partitioning (Python).
    • Experimental code for implicit solvent models parameter optimization (Julia).
    • Contribution to a code for robust direct minimization schemes (Julia, Fortran) in the Restricted Open-Shell Hartree Fock method (instead of SCF self-consistent techniques) with applications to the simulation of heavy metals and other open-shell systems.

    Member of the organization board of Young Researcher and Machine Learning CERMICS seminars.

    Contact : robert.benda@enpc.fr

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