Various research internships are available in the ab initio group at the Institut de Physique du Globe de Paris or at the University of Oslo. A few examples are detailed below. The internships last between 2 and 6 months, and you will receive financial support according to the standard rules and regulations of the university. For all internships, experience with unix/linux and preferably python and solid knowledge of condensed matter physics and chemistry are required. Previous experience with first-principles simulations is preferred.
Melting and vaporization processes during the large impacts of accretion in the early solar system
The early solar system was dominated by violent impacts between bodies of various sizes and compositions. The most extreme impacts, similar to the giant impact between the proto-Earth and Theia, led to the formation of huge protolunar disks, from which planets and moons condensed. Even impacts between large planetesimals could produce melting and partial vaporization. In case such impacts occurred close to the Sun, where the disk was already depleted by hydrogen, it is possible that part of this vapor phase was lost to space; the initial composition of the disk, and of the original bodies, is lost.
Here we attempt to reconstruct the chemical trajectory of impacts on specific planetesimals. The internship offers opportunities of acquiring both thermodynamic and computational skills, of learning the chemical-physics specifics to liquid-vapor equilibria, and of providing important planetological constraints on specific bodies of our solar system.
Supercritical state and evaporation in the silica-water system
The aim of this master stage is to analyze a large dataset of ab initio molecular dynamics simulations performed on the SiO2-H2O, which is the archetype of all hydrous silicate systems. The simulations span a wide temperature and pressure range that cover the liquid spinodal line, the liquid-vapor equilibrium curve, and the critical point. We will look at the thermodynamic and transport properties as a function of pressure, temperature, and composition. We will analyze in detail the chemical speciation in the fluid. We will monitor the decomposition, the speciation in the gas phase, and the liquid-vapor relations.
The entire analysis is performed using the open-source UMD package (https://tinyurl.com/3ac75mc8), which is developed on site. Depending on the results, further large-scale first-principles molecular dynamics calculations might be necessary.
Comparison of the supercritical state of tectosilicates
We analyze a large dataset of ab initio molecular dynamics simulations performed on silica and feldspars. The simulations span a wide temperature and pressure range that cover the liquid spinodal line, the liquid-vapor equilibrium curve, and the critical point. We will look at the thermodynamic and transport properties as a function of pressure, temperature, and composition. We will analyze in detail the chemical speciation in the fluid. We will monitor the decomposition, the speciation in the gas phase, and the liquid-vapor relations.
The entire analysis is performed using the open-source UMD package (https://tinyurl.com/3ac75mc8), which is developed on site. Depending on the results, further large-scale first-principles molecular dynamics calculations might be necessary.
Evaporation and condensation of selected refractory minerals
We analyze a large dataset of ab initio molecular dynamics simulations performed on several refractory minerals. We compute the position of the critical points. We analyze in detail the speciation of the vapor phase and the chemistry developing at the liquid-vapor interface. We will look at the thermodynamic and transport properties as a function of pressure, temperature, and composition.
The entire analysis is performed using the open-source UMD package (https://tinyurl.com/3ac75mc8), which is developed on site. Depending on the results, further large-scale first-principles molecular dynamics calculations might be necessary.
Calculation of the entropy within the protolunar disk
In this internship, we will calculate the amount of entropy that can be stored in the protolunar disk as a result of such a giant impact. During an impact, the pressure and temperature of a material evolve along a Hugoniot equation of state. The position along the Hugoniot is determined by the parameters of the impact, of the target, and of the impactor. We model the composition of the proto-Earth and of Theia with pyrolytic composition, as an approximant for the bulk silicate Earth. We choose a couple of representative points along the Hugoniot (shock) equation of state of pyrolite.
For this, we will use a combination of ab initio molecular dynamics simulations and thermodynamic integration to obtain the free energy and the entropy of a pyrolytic fluid at the conditions attained during the impact.
Minerals as new functional materials
We search for new ferroic materials with inspiration from the mineral world. We plan to work on selected sulfide and sulfosalt minerals and check their potential to develop piezoelectricity, ferroelectricity, and/or ferromagnetism. We will compute their static properties, like electronic, magnetic, and elastic. These results provide further constraints and help reduce the initial selection of minerals. In a further step, we compute the dielectric and dynamical properties of the most favorable minerals. The most promising candidates will serve as future starting materials for a campaign of actual synthesis and single-crystal measurements. The simulations will be performed using the ABINIT package and will be run on the machines from the national supercomputer centers.
Theoretical identification of perchlorate minerals on the surface of Mars
The Mars rovers showed the presence of surface mineralogy that in many respects is different from the one on the surface of our planet. In particular, the dry Martian atmosphere favors the development of a series of characteristic minerals, like perchlorates, which are hard to synthesize and stabilize in the Earth’s atmospheric conditions. The presence of perchlorates was suggested by Raman spectrometry.
Here we want to perform a systematic study of the vibrational properties of various perchlorate minerals. We will calculate the Raman and infrared spectra using the density functional perturbation theory as implemented in the ABINIT package. We will identify the representative peaks that can be used in identification, will analyze the displacement patterns associated with the vibrations, and will relate the chemical and hydration variations with changes in the spectra.
The results will be integrated into the WURM database (https://wurm.info/) and made available to the entire community.
Diffusion of noble gases in diamond
Diamond is a very hard and strong material, but it is not impermeable. In fact, various volatiles can diffuse through diamond under the right conditions. However, the rate at which these volatile diffuse is relatively slow compared to their diffusion in other materials. In particular, the diffusion of helium or other noble gases in diamond is a relatively slow process. The exact speed at which they diffuse through diamond depends on a variety of factors, including the temperature and pressure of the diamond, the presence of other point defects and impurities, as well as their concentration within the diamond. Once brought to the surface, the diamonds contain important clues about the rate of production of radioactive isotopes of noble gases.
Here we will perform first-principles molecular dynamics simulations and compare them with results from nudge elastic band calculations to estimate the rate of diffusion of He in diamond. We will look at the transport properties as a function of pressure, temperature, and content.
The internship is in collaboration with Martha Pamato (University of Padova). There is a possibility to extend the internship with a PhD degree, funded via the ERC INHERIT project, awarded to Martha Pamato (https://www.unipd.it/en/erc-pamato-inherit).