[CP2K-user] Post-doc in Toulouse, France

[Merlin Meheut]

Dear all, 

I have a new two years postdoctoral position in my group. 
Please see below for further information and links
Best Regards,

Title: Molecular simulations to predict the fractionation of isotopes in 
the environment (GET)

Applications are invited for a Postdoctoral Research Associate at Toulouse 
University (GET laboratory), working with Dr Merlin Méheut ( 
https://www.get.omp.eu/author/merlin-meheut/ ) and Dr Magali Benoît (CEMES, 
Toulouse), in the framework of an ANR “Young Researcher” project. We are 
looking for talented and highly motivated candidates to realize molecular 
dynamics calculations (both empirical and ab initio) for Environmental 
Sciences. The Associate will collaborate with experimental scientists at 
GET (Coll G Saldi, J Schott) and LHyGeS, Strasbourg (Coll A.D Schmitt), and 
with chemical theoricists at ENS, Paris  (coll R. Vuilleumier), NYU (M. 
Tuckerman) and CMC, Strasbourg (R. Schurhammer). Candidates motivated by 
multidisciplinary research and application of atomistic simulation to 
complex natural systems will be appreciated. 

To apply for this position, please connect to the following link : 
https://bit.ly/3oo5NyI

*Scientific context* 
Isotopic compositions of natural phases constitute a tool of primary 
importance to assess geological history. Recent progresses in mass 
spectrometry and analytical chemistry have enabled the detection of 
isotopic variations of a host of elements (e.g. Fe, Mg, Ca, Li, Zn), 
opening the path to numerous applications. In particular, Ca isotopes have 
shown their potential for medical applications (early diagnosis of 
decalcification), to assess mechanisms occuring at the soil-plant 
interface, or to assess the Ca cycle in the environment.

To take the full extent of these new measurements, it is necessary to 
precisely constrain the isotopic effect associated with elementary 
processes occuring at the atomic level. In this perspective, the 
fractionation of isotopes reached at thermodynamical equilibrium (called 
equilibrium fractionation) between two phases (between one mineral and a 
dissolved species, or between two dissolved species) is of particular 
interest.

It is possible to estimate isotopic fractionation based on atomistic 
modeling by estimating the thermo-kinetic properties of atoms in a given 
bonding environment. For solids, these properties are generally estimated 
based on the harmonic approximation, starting from the vibrational 
frequencies of the mineral (e.g. Méheut and Schauble 2014). For liquids, we 
have developed an approach based on path integral molecular dynamics (PIMD, 
Dupuis et al 2017). This approach, which was applied to Li isotopes, is 
computationally very expensive, and that is why it has been limited so far 
to the use of empirical potentials to describe atomic interactions. 

Our primary goal is to set an affordable numerical scheme to compute 
equilibrium fractionation properties of any material, in particular 
dissolved species, based on path integral molecular dynamics methods, but 
with atomic bonding described by ab initio electronic structure 
computations (instead of empirical potentials), so as to render its 
application to virtually any case. This approach will be first tested on 
the Ca²⁺-H2O system for which experimental data exist.

*Description of the position:*
The work of the researcher will be to set up path integral molecular 
dynamics on a Ca2+-H2O system, with empirical potentials (with the CP2K 
code), in order to compute Ca isotopes fractionation properties for this 
system. This will be first realized with empirical potentials, then with an 
ab initio approach. Depending on the avancement, another task of the 
postdoc may be to realize some calculations on solids, based on the 
well-controlled approach based on the harmonic approximation. 
To apply for this position, please connect to the following link : 
https://bit.ly/3oo5NyI 

CV and motivation letter will be requested. 

*Required technical skills:*
- Use of ab initio molecular dynamics codes: CP2K, CPMD, CP, PINY-MD. Good 
level. 
- Possibly expertise to build empirical potentials by inverse Monte Carlo 
approach.
- Possibly experience in path integral molecular dynamics.

*Knowledge to put in application:*
- Operating molecular dynamics algorithms 
- Path integral formulation of quantum mechanics.

*Know-how :*
- Computer programming : good level 
- Developing a scientific approach to set up a methodology aiming at 
reproducing a quantity measured experimentally. 
- Estimating the different sources of error and their consequences on the 
final result.

*Some papers in relation to the proposed work:*:
Dupuis R., Benoît M, Tuckerman M, Méheut M. (2017), Accounts of chemical 
research 50 (7), 1597-1605
Méheut M. and Schauble E.S. (2014), Geochimica et Cosmochimica Acta 134, 
137-154



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