Home
12th Apr, 2024: Schöntal symposium on dislocation plasticity
Are you coming to the Schöntal symposium on dislocation plasticity (https://lnkd.in/eNbt3rDq) next week?
Glad to present our collaborative work about dislocation-based plasticity in uranium dioxide (monday afternoon) as well as a poster about Pyrough: the free software we have built (https://lnkd.in/edkcHC8q) to design virtual samples with rough surfaces! See you there!
#CNRS #AMU #IM2NP #CEA #Dislocations #Plasticity #Pyrough #UO2
2-4 Apr, 2024: Plasticité 2024 conference
We were delighted to organise the Plasticité 2024 conference at the Pharo Gardens in Marseille. Thank you all for your participation.
Fig. Plasticité 2024 conference picture
5th March, 2024: TMS 2024
Here it is ! We are in Orlando with Hugo Iteney and a couple of colleagues from CEA Cadarache.
Hugo will give a talk on Wednesday at 9:20 a.m. (nanoscale mechanics session) about the influence of surface state on the mechanics of nano-objects.
I will give mine about plastic anisotropy in UO2 fuel single crystal on thursday 1:30 p.m. (nuclear fuel session).
We also have a poster (monday evening session) about Pyrough, the tool we developed to design 3D sample with rough surfaces for MD and FEM simulations.
Note the schedule of Dr. Pivano's talk about our collaborative work on dislocations in UO2 computed by atomistic simulations on thursday 1:00 p.m. (nuclear fuel session).
See you there !
20th Feb, 2024: Mixed-climb observed by TEM in uranium dioxide deformed at 1550°C
In this study recently published in Scripta Materialia, transmission electron microscopy characterization was carried out on polycrystalline UO2 pellets after uniaxial compression tests performed at constant strain rate and 1550°C. The detailed characterization of dislocation motion provides insights on the deformation processes operating at the nanoscale that are critical to better understand the viscoplastic response of the UO2 nuclear fuel during off-normal power transient. Results emphasize the complexity of dislocation motion at high temperature since it involves glide and a mixedmechanism involving climb, called mixed climb, which was not evidenced earlier in this material. Congrats Claire and all the team !
C. Onofri, J.P. Monchoux, J. Amodeo, R. Madec, C. Sabathier, H. Palancher, J. Fouet, D. Drouan, M. Legros, Versatility of dislocation motions in polycrystalline UO2 deformed at 1550 °C investigated by TEM, Scr. Mater. 244 (2024) 116034. (50d-free access) (journal)
Fig. TEM observation of the mixed climb process in UO2 deformed at 1550°C
14th November, 2023: Femtosecond-laser devitrification of CuZr glass, new article in Acta Materialia
The ultrafast laser-induced local devitrification in metallic glass is an intricate phenomenon with untapped potential in nanotechnology. In Iabbaden et al., a study recently published in Acta Materialia, we combine the two-temperature model with classical molecular dynamics simulation to elucidate the mechanisms steering localized phase transitions in CuZr metallic glasses. Intriguingly, during the nonequilibrium thermodynamic processes induced by laser energy deposition, the atomic environment is rearranged with well-defined thermomechanical conditions fostering the emergence of a stable and ordered solid solution. The concerted impact of the compressive pressure wave and rapid heating, resulting from the ultrafast laser significantly disrupts the glass microstructure initiating the devitrification process. Congratulations Djafar for these very nice results!
Iabbaden, D., Amodeo, J., Fusco, C., Garrelie, F., & Colombier, J. P. (2023). Dynamics of Cu-Zr metallic glass devitrification under ultrafast laser excitation revealed by atomistic modeling. Acta Materialia, 119487. (preprint) (50d-free access) (journal)
14th November, 2023: Femtosecond-laser devitrification of CuZr glass, new article in Acta Materialia
The ultrafast laser-induced local devitrification in metallic glass is an intricate phenomenon with untapped potential in nanotechnology. In Iabbaden et al., a study recently published in Acta Materialia, we combine the two-temperature model with classical molecular dynamics simulation to elucidate the mechanisms steering localized phase transitions in CuZr metallic glasses. Intriguingly, during the nonequilibrium thermodynamic processes induced by laser energy deposition, the atomic environment is rearranged with well-defined thermomechanical conditions fostering the emergence of a stable and ordered solid solution. The concerted impact of the compressive pressure wave and rapid heating, resulting from the ultrafast laser significantly disrupts the glass microstructure initiating the devitrification process. Congratulations Djafar for these very nice results!
Iabbaden, D., Amodeo, J., Fusco, C., Garrelie, F., & Colombier, J. P. (2023). Dynamics of Cu-Zr metallic glass devitrification under ultrafast laser excitation revealed by atomistic modeling. Acta Materialia, 119487. (preprint) (50d-free access) (journal)
7th Nov, 2023: attending the NuFuel conference in Marseille, France
Jules-Elemir Suchorski (Ph.D. applicant) and myself will attend the Nufuel workshop from today to thursday, in Marseille (France). Nufuel is an international meeting focusing on nuclear fuels. We will present our results on the atomistic modeling of the screw dislocation core and mobility in UO2 (Jules, tomorrow 2PM) and on the modeling of the plastic anisotropy (still in UO2! myself, tomorrow 11:40 AM). Stay tuned!
24th October, 2023: Pyrough, a tool to build 3D samples with rough surfaces
No matter the scale, surface roughness plays a crucial role in various fields of applications such as mechanical engineering, lubrication, catalysis or machining. In this study, we introduce you to Pyrough, a new tool to build 3D samples with rough surfaces for atomistic and finite-element simulations. Pyrough is open source (you can get it from my Github repository) and relies on the classical roughness theory. Several basic shapes including basic blocks, spheres, grains and wires with self-affine surface asperities are implemented and the object-oriented structure of the program simplifies the implementation of more complex shapes. Virtual sample design is improved using Pyrough, which enables more realistic simulations to be made. Several application examples including e.g., the design of wavy grain boundaries or nanoindentation testing using a roughened indenter tip are presented in ther article.
H. Iteney, J.A.G. Joa, C.L. Bourlot, T.W. Cornelius, O. Thomas, J. Amodeo, Pyrough: A tool to build 3D samples with rough surfaces for atomistic and finite-element simulations, Comput. Phys. Commun. (2023) 108958 (50 days free access) (preprint)
Fig. Pyrough : A tool to build 3D samples with rough surfaces for atomistic and finite-element simulations
23rd October, 2023: Fang/MNO group virtual workshop
Very instructive scientific time this morning during a virtual workshop with members from Xufei Fang's group in Darmstadt and the MNO group in Marseille.
7th September, 2023: ERC TimeMan meeting in Lille, France
Such a good time in Lille at the Timeman meeting organized by Pr. Patrick Cordier and co at Institut Chevreul, Univ of Lille. Two days discussing how crystalline and amorphous oxides, rocks, and metals deform under extreme temperature, pressure, or strain rate conditions. It was so good to see you guys again, thank you :)
24th July, 2023: New article about UO2 irradiation-induced hardening published in International Journal of Plasticity
What is the influence of irradiation loops on the mechanical behaviour of UO2 nuclear fuel?
Plasticity of irradiated UO2 is of major interest to improve the risk assessment of the nuclear fuel cladding failure in the case of design basis accidents. In this study recently published in International Journal of Plasticity, we investigate the main irradiation-hardening processes induced by {110} irradiation loops interacting with glissile dislocations of the primary slip system, 1/2<110>{001}, of UO2. The interactions are simulated at two scales using molecular dynamics and discrete dislocation dynamics, to characterise local interactions and identify strengthening configurations as a function of the dislocation-irradiation loop geometry. In particular, we show that 1/2<110>{001} screw dislocations can be strongly pinned by helical turn configurations. Statistical large-scale discrete dislocation simulations are performed to investigate the collective behaviour of a large density of irradiation defects and quantify irradiation hardening. Several microstructural processes including loop drag and shovelling are observed and their involvement in clear band formation and hardening of UO2 fuel at high temperature is discussed.
Fig. Interaction between a 1/2[-110](001) screw dislocation and a 1/2[110](110) prismatic loop (case #5, 𝛽 = 90° , 𝑙𝑏 = 50 Å). (a-c) MD simulation. (d-f)DDD simulation with cross-slip. (g-i) DDD simulation with cross-slip turned off.
26th June, 2023: How do ceria nanoparticles deform?
Ceria is a ceramic that is well known for its catalytic properties. Often shaped from a nanometric powder, it also has particularly remarkable mechanical properties. In this study recenlyt published in Materialia, we show how small ceria nanocubes deform under the effect of an uniaxial stress.
In particular, we have demonstrated a transition from a phase transition deformation mechanism in sub-10 nm samples to unexpected plasticity processes in the {111} crystallographic planes in the larger samples.
Thanks to Dr. Gaetan Laurens and Dr. Tristan Albaret from ILM Lyon for the nice collaboration.
https://www.sciencedirect.com/science/article/abs/pii/S2589152923001515
Fig. Size-dependent plasticity in ceria nanocubes
Fig. Influence of cross-slip on the plastic anisotropy of UO2 single crystal
9th June, 2023: New article in Acta Materialia !
Cross-slip and composite slip responsible for the plastic anisotropy of UO2 single crystal at high temperature? That's the hypothesis we investigate using discrete dislocation dynamics and crystal plasticity modeling in our new article published in Acta Materialia.
https://www.sciencedirect.com/science/article/pii/S1359645423003476?dgcid=coauthor
16th May, 2023: Coupling DDD and FEM to reach mesoscale modeling of nano-objects (new article)
Modeling the mechanics of nano-objects is generally done using the molecular dynamics (MD) simulation method. However, this approach suffers from size and time scale constraints that make the one-to-one comparison to the experiment particularly difficult.
In Gonzalez-Joa et al. Modelling Simul. Mater. Sci. Eng. 31 (2023) 055003, we use the superposition approach to couple the discrete dislocation dynamics method to finite-element, leading to a new tool called El-Numodis that allows us to get rid of MD limitations. El-Numodis was specially designed to manage nano-objects deformation including dedicated features as a Monte-Carlo-based dislocation nucleation subroutine and the mirror dislocation concept. The article presents the main features of the code as well as numerical test cases and benchmarks going from classical boundary value problems to tensile tests on model thin film.
Check this out : https://iopscience.iop.org/article/10.1088/1361-651X/acd01b or from my Publications page.
Congrats Javier !
Fig. Influence of surfaces on the mechanical response of a thin film under tension
25th April, 2023: COST MecaNano first general meeting at IMDEA Materials in Madrid, Spain
I will be at the COST MecaNano first general meeting at IMDEA Materials in Madrid from tonight to next Friday. I will present our work on the influence of roughness on the mechanics of nano-objects Thursday 27th April at 11:20. Can't wait to be there ;)
6th April, 2023: Hugo and I at the Plasticité conférence in Lyon (France)
Hugo Iteney did present his results on surface roughness and nanomechanics at the Plasticité conference in Lyon (France).
I am also glad to have participated to the conference presenting our work on the coupling between the DDD code Numodis and FEM for nanomechanical applications.
1st February, 2023: Congratulations Djafar !
Congratulations to Djafar Iabbaden who has successfully defended his PhD thesis last friday at the university Jean Monnet of Saint-Etienne.
His work focused on modeling ultra-fast laser pulse and glass devitrification processes using a two-temperature model coupled to molecular dynamics simulations.
This work was superised Jean-Philippe Colombier and Florence Garélie at the LHC lab', university Jean Monnet of Saint-Etienne.
It was a pleasure to be one of your collaborator during this trip.
You can still have a look to his outstanding paper recently published in PRM !
3rd January, 2023: load-controlled versus displacement-controlled nanomechanics, new article in Scripta Materialia
Molecular simulations in nanomechanics are still performed in displacement-controlled mode while many experiments are still force-controlled. Why is this so? It was necessary to change things ;)
In this work published in Scripta Materialia, we control the force imposed by a virtual indentor using a feedback loop driven in Python to compress different types of metallic nanoparticles. The results show significant differences with what was obtained so far with controlled displacement, especially in terms of dislocation densities and dynamics. Congratulations to Hugo Iteney who signs here his first scientific paper.
The article can be found here or in the bib section of the website.
Fig. Shape and dislocation miscrotructure evolution in a gold nanoparticle under compression using load-controlled (top) and displacement-controlled (bottom) MD simulations. Atoms colored in gold and red respectively refer to surfaces and stacking-fault environments. From Iteney et al. Scripta Materialia 2023.
1st January, 2023: Happy new year !!!
I wish you all the best for 2023 !!!
13th December, 2022: Javier Gonzalez PhD defense
Congratulations to Javier Gonzalez who successfully defended his PhD thesis yesterday.
His work focused on coupling the discrete dislocation dynamics code NUMODIS (L. Dupuy, CEA Saclay, France) to the finite-element code Elmer (P. Rabäck, Espoo, Finland) applied to nanomechanical simulations as e.g., the nucleation of dislocation in ceramic nanoparticles under compression.
This work was co-superised by Michel Perez (INSA-Lyon, MATEIS) and myself.
Congratulations Javier !
9th December, 2022: Marion Borde PhD defense
Congratulations to Marion Borde who successfully defended her PhD thesis a few days ago. Her work focused on the modeling of dislocations in UO2 and their interactions with irradiation defects was supervised by Bruno Michel (CEA), David Rodney (Univ. Lyon 1) and myself .
You can have a look to her first paper that pops out the day of defense in JNM (link below).
This work is of great interest for the future of our fission power plants. Congratulations Marion !
link towards the article : https://www.sciencedirect.com/science/article/abs/pii/S0022311522006365?via%3Dihub
Fig. Transformation of the edge {001} dislocation core into a zigzag configuration at high-temperature.
28th November, 2022: Dislocation core and mobility in UO2, new article in JNM
The work of Marion Borde and collaborators about the edge 1/2<110>{ 001} dislocation is available pre-proof in Journal of Nuclear Materials.
In a nutshell, this study emphasizes the occurence of a new edge {001} dislocation core structure in UO2 stable at high-temperature and its mobility based on atomistic simulations and DFT. Congratulations Marion !
Check this out !
https://www.sciencedirect.com/science/article/abs/pii/S0022311522006365?via%3Dihub
1st Oct, 2022: with the team @MMM10 in Baltimore, USA
Hugo, Marion and myself are in Baltimore (USA) for the MMM10 conference about multi-scale materials modeling.
I will start presenting the study we did in collaboration with Olivier Thomas and Eugen Rabkin's group about nanoparticles strengthening by coating on monday 11:10 AM (metals at the nanoscale session). Then, Hugo will speak about Pyrough, a new tool we developed to model roughness, monday evening at 4:50 PM (metals at the nanoscale session). Finally, Marion will present her work on UO2 plastic deformation under irradiation on wednesday 5th, 2:55 PM (nuclear materials session). Hugo and I will also present posters about force-controlled MD nanocompression and El-Numodis, a new DD/FEM toold we developed during Javier Gonzalez' PhD thesis, in collaboration with Laurent Dupuy and Peter Raback.
I also send force to Ronan Madec who will present a work we did in collaboration on the mesoscale modeling of UO2 plasticity on wednesday afternoon, 4:50PM (nuclear materials session)
The program of the conference can be found here.
Enjoy !
2nd September, 2022: Thank you MATEIS !
After 9 years serving first as post-doc and then as CNRS researcher, I am now moving from MATEIS lab (INSA-Lyon) to IM2NP (Aix-Marseille University). I would like to warmely thank every people I've met at MATEIS and in nearby laboratories. MATEIS and more generally the INSA and the University of Lyon have been particularly pleasant places both from a professional and personal point of view. Thank you all and let's go for new adventures.
25th May, 2022: Marion Borde @Cosires 2022
Hi from the Porquerolles island where Marion presents her results about dislocation and irradiation defects modeling in uranium dioxide. Exciting conference and amazing place !
The program of the conference can be found here
6th May, 2022: New PhD offer on multi-scale modeling of dislocation and irradiation defects in UO2
A new PhD offer is available starting next automn (approximately) @CEA Cadarache and @IM2NP AMU Marseille. The PhD student will be supervized by B. Michel, A. Pivano @CEA Cadarache and myself @CNRS. Contact me with CV and Master quotes if interested.
More information in the following.
4th May, 2022: demi-ATER position opened
A 1y demi-ATER position (teaching and research in physics) will open next autumn in the MNO group at Aix-Marseille University. Please contact me with CV if interesting in teaching physics and modeling nanomechanics (experience required).
31st March, 2022: Talks next week @Plasticité 2002 in Toulouse, France
Hugo Iteney and Marion Borde will give talks next wednesday morning @Plasticité 2022 in Toulouse (France) ! In particular, they will talk about modeling force vs displacement-controlled nanomechanics experiments and dislocation and irradiation in UO2. Come to see them !
22nd March, 2022: New email adress !
check "About me" section
Coming soon: lets talk @Saint-Gobain Research Provence and @CINaM
I will be @St-Gobain Research Provence (Cavaillon, France) next March 17th and then @CINaM (Marseille, France) March 21st to give presentations respectively on the small-scale modeling of ceramics and nanocrystals.
Fig. α-Al2O3 alumina crystal structure at the atomc scale
January 25th 2022: New article about interatomic potential transferability to nanomechanics for alumina accepted in MSMSE
Congratulations to Dr. Qinqin Xu for his study about about atomistic simulations and interatomic potential comparisons in alumina published in the MSMSE journal. Congratulations again for your PhD defense !
https://iopscience.iop.org/article/10.1088/1361-651X/ac4d76/meta
Fig. TEM imaging 160 nm below UO2 sample surface implanted with cesium and annealed at high-temperature. Colored circles refer to various kinds of nanobubbles.
January 17th 2022: New article about Cs diffusion in UO2 accepted in the JCP
New article about Cs diffusion processes in UO2, a combined study crossing SIMS, TEM analysis and atomistic simulations. Congratulations Clementine & co !
January 3rd 2022: Happy new year !!!
I wish you and your families all the best for 2022 ! Lets hope to jump (as a kink-pair!) out of the pandemia as soon as possible.
December 16th 2021: Congratulations Qinqin !
Exactly 10 years after my own defense, Dr. Qinqin Xu received his PhD degree from INSA-Lyon for his thesis entitled "Dislocation and nanomechanics in Al2O3 using atomistic simulations". Congratulations Qinqin !
Dr. Qinqin Xu (second on the righ) and his PhD jury and supervisors. From left to right: Pr. Jérome Chevalier (INSA-Lyon, supervisor), Pr. Philippe Carrez (Univ. Lille 1, reviewer), Dr. Tristan Alabaret (Univ. Lyon, invited), Dr. Laurent Pizzagalli (Univ. Poitiers, reviewer), Dr. Marine-Ingrid Richard (CEA Grenoble, exminator), Pr. Karine Masenelli-Varlot (INS-Lyon, president), Dr. Qinqin Xu (INSA-Lyon) and myself.
November 18th 2021: Qinqin Xu PhD defense
Qinqin Xu was recently authorized to defend his PhD thesis entitled "Dislocation and nanomechanics in Al2O3 using atomistic simulations". He will defend at INSA-Lyon, Ouest amphitheater, December 14th at 9.30 AM.
October 14th 2021: virtual seminar @UMET, Univ. Lille
The seminar will be on Thursday 14 October 2021 at 4pm (Paris)
Title: On the influence of shape and nanostructure on the mechanics of nanoparticles
In recent years, several groups focused on probing the strength, ductility and deformation processes of nanoparticles using molecular dynamics simulations specially to support compression tests within the electron microscopes. Now, studies deal with most of materials classes including metals, ceramics and semi-conductors.
In this talk, I will first present the main features of nanoparticles mechanical properties and elementary deformation processes mostly based on recent studies published in the field. A specific attention will be paid to the influence of freshly-identified key parameters such as shape and surface structuration relying on atomic-scale and dislocation dynamics simulations performed in my group.
Follow this link for the video of the seminar: https://pod.univ-lille.fr/video/22021-14-october-2021-timeman-seminar-jonathan-amodeo/
September 2nd 2021: Soon @Euromat2021 13-17 September
Together with Javier Gonzalez we will attend the Euromat2021 (virtual) conference next September 13-17. Javier will give a talk about El-Numodis, the DD/FEM tool he developped during his PhD (Sept 17th, 11:50 AM) while I will present new results on the weakening of core-shell nanoparticles recently published in ACS Nano (Sept 17th, 1:10 PM). Both presentations will be given within the Symposium D3: Micro- and Nano-mechanics – Characterization and Modelling (André Clausner, Venera Maier-Kiener and Jon Molina).
August 22nd 2021: When more is less, new paper in ACS Nano
When more is less: it is well-known that in the case of bulk polycrystalline metals, a reduction in the grain size leads to material hardening, since the grain boundaries represent efficient barriers for slip transfer between the adjacent crystalline grains. In this work published with Pr. Rabkin (Technion Univ.), we used SEM compression tests and MD simulations to show that coating single crystalline Ag nanoparticles with a thin polycrystalline Au layer leads to a weakening of the particles. The results of this study show that adding imperfect material to superstrong single crystalline metal nanoparticles makes them weaker. At the same time, thin nanocrystalline coatings can be employed to improve the formability of metals at the nanoscale.
This study was recently published in ACS Nano:
When More Is Less: Plastic Weakening of Single Crystalline Ag Nanoparticles by the Polycrystalline Au Shell
June 29th 2021: Soon @Euromat2021 conference
Together with Javier Gonzalez we will attend the Euromat2021 (virtual) conference next September 12-16. Javier will give a talk about El-Numodis, the DD/FEM tool he developped during his PhD while I will present new results on AgAu core-shell nanoparticles we obtained together with E. Rabkin and other colleagues. Both presentations will be given within the Symposium D3: Micro- and Nano-mechanics – Characterization and Modelling (André Clausner, Venera Maier-Kiener and Jon Molina). More information to come.
May 25th 2021: Review article about modeling mechanics of nanoparticles published in Comptes Rendus Physique
I am glad to announce you the publication of the review article I recently wrote together with Laurent Pizzagalli (P' Institute, France) about how to model the mechanical properties and deformation processes of nanoparticles. It is published in the french Académie des Sciences journal Compte Rendus Physique. Enjoy !
Amodeo, J. & Pizzagalli, L. Modeling the mechanical properties of nanoparticles: a review. Comptes Rendus Physique 22, 1–32 (2021).
https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.70/
Multi-scale modeling of nanoparticle mechanics
Surface dislocation nucleation energy and rate in a MgO nanoparticle
May 10th 2021: New article published in Nature NPJ Computational Materials
After few years working on that project with Emile Maras and David Rodney, I am glad to announce our new article published in Nature NPJ computation materials. This work is about the site-dependence of dislocation nucleation in nanoparticles. Enjoy !
Amodeo, J., Maras, E. & Rodney, D. Site dependence of surface dislocation nucleation in ceramic nanoparticles. npj Comput Mater 7, 60 (2021).
https://www.nature.com/articles/s41524-021-00530-8
May 3rd 2021: New website version available online
April 30th 2021: SASHA ANR kick-off : welcome Hugo Iteney !
Hugo just joined our group as a PhD student @MATEIS and @IM2NP in the context of the SASHA ANR JCJC project. Hugo will work on modeling nano-objects surface states and their consequences on mechanical properties. Welcome Hugo !!!
March 26th 2021: IOP best reviewer award
Thank you IOP and Modeling and Simulation in Materials Science and Engineering (MSMSE) for the acknowledgements.
March 22nd 2021: Talk @TMS2021
Here is a link towards the talk I gave at #TMS2021 last week : talk_TMS2021
It is entitled "Modeling mechanics of nanoparticles: eveything but size".
Enjoy ! #TMS2021
TEM imaging of MgO nanocubes under compression
March 5th 2021: MgO nanoparticles in the TEM : new article in MRL !
From dislocation nuclceation to dislocation multiplication in MgO ceramic nanoparticle.
Congrats to Inas Issa and all co-authors for this nice work published in Materials Research Letters.
Here is the link to the open access.
March 22nd 2021: TMS 2021 Conference
Hi everyone !
I have been invited to give a talk at the next TMS conference happening next March 15-18th (virtual).
It is scheduled March 17th, 1:30 PM (Paris time), in the"100 Years and Still Cracking: A Griffith Fracture Symposium: Fracture and Cracks" session.
My presentation, co-authored with Laurent Pizzagalli (P' institute, CNRS, France), is entitled "Modeling mechanics of nanoparticles: everything but size".
I hope to see there... in the chat ! ;)
Link to the conference website !
Force field fitting errors and Janus core-shell nanoparticles
Nov 18th 2020: New article accepted about machine learning force fields transferability applied to AuFe nanoparticles
M. Benoit, J. Amodeo, S. Combettes, I. Khaled, A. Roux and J. Lam, Measuring transferability issues in machine-learning force fields: The example of Gold-Iron interactions with linearized potentials, Mach Learn Sci Tchnol
https://iopscience.iop.org/article/10.1088/2632-2153/abc9fd/meta
Machine-learning force fields have been increasingly employed in order to extend the possibility of current first-principles calculations. However, the transferability of the obtained potential can not always be guaranteed in situations that are outside the original database. To study such limitation, we examined the very difficult case of the interactions in gold-iron nanoparticles. For the machine-learning potential, we employed a linearized formulation that is parameterized using a penalizing regression scheme which allows us to control the complexity of the obtained potential. We showed that while having a more complex potential allows for a better agreement with the training database, it can also lead to overfitting issues and a lower accuracy in untrained systems.
Nov 12th 2020: SASHA granted by the ANR
The SASHA project about SurfAce State and mecHanics of nAno-objects has been granted by the french ANR (JCJC).
During the next 4 years, we will do our best to improve the design and modeling of nano-objects, accounting for surface specs.
Interns and PhD positions in the group will open soon ! :)
Sept 9th 2020: New article accepted about machine learning force fields transferability applied to AuFe nanoparticles
M. Benoit, J. Amodeo, S. Combettes, I. Khaled, A. Roux and J. Lam, Measuring transferability issues in machine-learning force fields: The example of Gold-Iron interactions with linearized potentials, Mach Learn Sci Tchnol
https://iopscience.iop.org/article/10.1088/2632-2153/abc9fd/meta
Machine-learning force fields have been increasingly employed in order to extend the possibility of current first-principles calculations. However, the transferability of the obtained potential can not always be guaranteed in situations that are outside the original database. To study such limitation, we examined the very difficult case of the interactions in gold-iron nanoparticles. For the machine-learning potential, we employed a linearized formulation that is parameterized using a penalizing regression scheme which allows us to control the complexity of the obtained potential. We showed that while having a more complex potential allows for a better agreement with the training database, it can also lead to overfitting issues and a lower accuracy in untrained systems.
Various freezing paths of Ni3Al nanoparticles
Evolution of dislocation interaction coefficients in the athermal regime of UO2
May 6th 2020: New article about dislocation strengthening in UO2 !
Portelette, L., Amodeo, J., Michel, B., & Madec, R. (2020). Athermal dislocation strengthening in UO2. Journal of Nuclear Materials, 152157.
https://www.sciencedirect.com/science/article/pii/S0022311519316411
Understanding the mechanical behavior of uranium dioxide (UO2) at high-temperature is of great interest to predict the behavior of the nuclear fuel under incidental operating conditions. Here, strengthening elementary processes and dislocation hardening coefficients are studied by the mean of Dislocation Dynamics (DD) simulations in UO2. The three slip modes of the fluorite structure i.e., ½<110>{100}, ½<110>{110} and ½<110>{111} are modelled and all the possible dislocation configurations are analyzed and discussed. Averaged hardening coefficients are derived and their sensitivity to the sample orientation is discussed in the light of the seminal experimental work of Sawbridge and Sykes. This DD study gives rise to new insights about UO2 mechanical behavior at high-temperature.
1st February, 2023: Congratulations Djafar !
Congratulations to Djafar Iabbaden who has successfully defended his PhD thesis last friday at the university Jean Monnet of Saint-Etienne.
His work focused on modeling ultra-fast laser pulse and glass devitrification processes using a two-temperature model coupled to molecular dynamics simulations.
This work was superised Jean-Philippe Colombier and Florence Garélie at the LHC lab', university Jean Monnet of Saint-Etienne.
It was a pleasure to be one of your collaborator during this trip.
You can still have a look to his outstanding paper recently published in PRM !