With emergence of nanotechnology, it is possible to control interfaces and flow at nanoscale. This is of particular interest in the Oil and Gas industry (O&G), where nanoscience can be applied on processes such as Enhance Oil Recovery (EOR) and oil mitigation. On this direction, one of potential strategies is the so called Nano-EOR based on surface drive flow, where mobilization of hydrocarbons trapped at the pore scale can be favored by controlling by the chemical environment through “wettability modifiers”, such as functionalized nanoparticles (NP) and surfactants. The challenge consists then to search for optimal functionalized NP for oil recovery and mitigation at the harsh conditions found in oil reservoirs. Here, we introduce a hierarchical computational protocol based on the role of NP interfacial and wetting properties within oil/brine/rock interfaces to the fluid displacement in pore network models (PNMs). This integrated multiscale computational protocol ranges from first principles calculations, to determine and benchmark interatomic potentials, which are coupled with molecular dynamics (MD) to characterize the descriptors (interfacial properties and viscosity). The MD results are then mapped into Lattice Boltzmann method (LBM) simulation parameters to model the oil displacement process in PNMs at the microscale. Here, we show that this multiscale protocol coupled with Machine Learning techniques can be a resourceful tool to explore the potentialities of chemical additives, such as NP and surfactants, for the oil recovery process and investigate the effects of interfacial tension and wetting properties on the fluid behavior at both nano and microscales.

Replacing liquid by solid state electrolytes has the potential to significantly improve current Li ion batteries concerning performance and safety. The material class NZP, based on the compound NaZr2(PO4)3, exhibits a structural framework suitable for ionic conduction. In this work, a systematic compositional screening and simulation approach, combining classical molecular-dynamics, first-principles calculations, and structural analysis was applied, with which a set of new Li ion conducting NZP compounds could be identified.

Because of steady increase in the availability of computing power, ab initio methods of computational materials science become everyday investigation tools in various research fields. This popularity of the first-principle-based atomistic modeling is in large part due to the performance of density functional theory (DFT), which could be used for simulations of chemically and structurally complex materials, including minerals, fluids and melts. However, because of intrinsic approximations, DFT is not always able to deliver reliable predictions. This is especially pronounced for f-elements bearing materials such as nuclear materials considered in nuclear waste management. Properties such as reaction enthalpies or electronic state are often badly predicted. In this contribution we discuss our experience with different computational methods, including the parameter free DFT+U method, in which the Hubbard U parameter is derived ab initio, for prediction of various properties of f electrons bearing materials. We show significant improvement obtained for structural and thermochemical parameters of various lanthanide-bearing ceramic materials and actinide-bearing molecular and solid compounds when the f electrons correlations are explicitly accounted for. Last, but not least, we demonstrate that complementary experimental and atomistic modeling studies result in superior and more complete characterization of challenging materials considered in nuclear waste management.

Bismuth displays puzzling superconducting properties. In its crystalline equilibrium phase, it does not seem to superconduct at accessible low temperatures. However, in the amorphous phase it displays superconductivity at ∼ 6 K. Under pressure bismuth has been found to superconduct at Tcs that go from 3.9 K to 8.5 K depending on the phase obtained. So the question is: what electronic or vibrational changes occur that explains this radical transformation in the conducting behavior of this material? In a recent publication we argue that changes in the density of electronic and vibrational states may account for the behavior observed in the amorphous phase with respect to the crystal. We have now undertaken an ab initio computational study of the effects of pressure alone maintaining the original crystalline structure and compressing our supercell computationally. From the results obtained we infer that if the crystal structure remains the same (except for the contraction), no superconductivity will appear.

There are growing interests on magnetic nanowires, due to their potential applications in magnetic sensors and recording devices. In this work, we report a comparative ab-initio study based on the Density Functional Theory (DFT) of Ni x Fe1-x nanowire periodic arrays by using atomic-orbital and plane-wave basis respectively through DMol3 and CASTEP codes. After performing the geometry optimization, we calculate the spin-polarized electronic density of states, average interatomic distance, and magnetic moments. For pure Ni nanowires (x = 1, the dependence of the magnetic moment obtained from CASTEP calculations on the cutoff energy, as well as that from DMol3 on the thermal smearing parameter is analyzed in detail. Both ab-initio calculations predict close magnetic moments for each x, being slightly larger those of DMol3 obtained with significantly less computing cost. Finally, these DFT results are compared with experimental data and a good agreement is observed.

Many computational and experimental analyses of molecular excitation rely on relative atomic velocities to identify the excitation of chemical bonds. These are often interpreted through the aid of normal mode calculations. We address two potential gaps in this approach: 1. Relative velocities may not reflect the total potential energy absorbed by the bond. 2. Normal mode calculations omit interactions between neighboring molecules, effectively assuming a similarity between condensed- and gas-phase chemistry. Phonon calculations implicitly include interactions between neighboring molecules and allow analyses of both relative velocities and potential energies in solids.In the present work, we compare kinetic and potential energy fractions of the phonon modes of the molecular solids nitromethane and β-HMX. We show that velocity-based methods are likely sufficient to analyze nitromethane. However, they cannot detect the majority of excitation ofthe N-N bonds in β-HMX, the scission of which appears to begin major decomposition pathways in the molecules.In the broader context of condensed-phase chemistry, this implies that important interactions may not all be identifiable through analyses that rely solely on relative atomic velocities.

Thermal batteries based on a reversible adsorption/desorption of a working fluid (water, methanol, ammonia) rather than the conventional vapor compression is a promising alternative to exploit waste thermal energy for heat reallocation. In this context, there is an increasing interest to find novel porous solids able to adsorb a high energy density of working fluid under low relative vapor pressure condition combined with an easy ability of regeneration (desorption) at low temperature, which are the major requirements for adsorption driven heat pumps and chillers. The porous crystalline hybrid materials named Metal–Organic Frameworks (MOF) represent a great source of inspiration for sorption based-applications owing to their tunable chemical and topological features associated with a large variability of pore sizes. Recently, we have designed a new MOF named MIL-160 (MIL stands for Materials of Institut Lavoisier), isostructural to CAU-10, built from the assembly of corner sharing aluminum chains octahedra AlO4(OH)2 with the 2,5-furandicarboxylic linker substituting the pristine organic linker, 1,4-benzenedicarboxylate. This ligand replacement strategy proved to enhance both the hydrophilicity of the MOF and its amount of water adsorbed at low p/p0. This designed solid was synthesized and its chemical stability/adsorption performances verified. Here, we have extended this study by incorporating other polar heterocyclic linkers and a comparative computational study of the water adsorption performances of these novel structures has been performed. To that purpose, the cell and geometry optimizations of all hypothetical frameworks were first performed at the density functional theory level and their water adsorption isotherms were further predicted by using force-field based Grand-Canonical Monte Carlo simulations. This study reveals the ease tunable water affinity of MOF for the desired application.