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We calculate the concentration-concentration partial structure factor S-CC(k) and the charge-charge structure factor S-zz(k) of liquid SiO2, amorphous SiSe2 and liquid GeSe2 using first-principles molecular dynamics. These systems are characterized by the occurrence of intermediate range order, as evidenced by a first sharp diffraction peak (FSDP) at low k values in the total neutron structure factor. We show that a FSDP in the concentration-concentration partial structure factor S-CC(k) is generally associated with a small departure from chemical order. This feature tends to vanish either when sufficiently high levels of structural disorder set in, or, oppositely, when the chemical order is essentially perfect. For none of these networks, a FSDP is observed in the charge-charge structure factor S-zz(k), i.e., fluctuations of charge do not occur over intermediate range distances. The constraint of charge neutrality is at the very origin of the appearance of fluctuations of concentration. These are observed when the atoms occur in configurations with different coordinations.

The microscopic origin of the intermediate phase in two prototypical covalently bonded A(x)B(1-x) network glass forming systems, where A=Ge or Si, B=Se, and 0

In a search for the physical origin of the first sharp diffraction peak (FSDP) in the concentration-concentration partial structure factor S-CC (k) of disordered network-forming materials, we perform first-principles molecular dynamics simulations of liquid GeSe4 (l-GeSe4) and liquid SiSe2 (l-SiSe2). These systems are designed to provide clues on the relationship between the appearance of an FSDP in the S-CC(k) structure factor and the degree of chemical order. Short-range chemical order is more pronounced in l-GeSe4 and in l-SiSe2 than in liquid GeSe2. For the latter system, our level of theory does not reproduce the FSDP in the experimentally observed SCC(k) structure factor. We find that a distinct FSDP shows up in the partial structure factor SCC (k) for l-GeSe4. In SCC (k) for l-SiSe2, we also find a feature at the FSDP location, although it is smaller compared to GeSe4. Given the tight correlation existing between chemical order and ionicity, these results suggest that the ionic character of the bonds plays a crucial role in inducing concentration fluctuations at intermediate-range distances.

The thermodynamic stability of hydroxylated graphane, that is, fully sp3 graphene derivatives coordinated with -H and -OH groups, has been recently demonstrated by ab initio calculations. Within the density functional theory approach, we investigate the electronic property modifications of graphane by progressive hydroxylation, that is, by progressively substituting -H with -OH groups. When 50% of graphane is hydroxylated, the energy bandgap reaches its largest value of 6.68 eV. The electronic affinity of 0.8 eV for graphane can widely change in the 0.28-1.60 eV range depending on the geometric configuration. Hydroxylated graphane has two interfaces with vacuum, hence its electron affinity can be different on each interface with the formation of an intrinsic dipole perpendicular to the monolayer. We envisage the possibility of using hydroxylated graphane allotropes with tunable electronic affinity to serve as interfacial layers in 2D material-based heterojunctions.

Laser-driven proton acceleration, as produced during the interaction of a high-intensity (I > 1 × 1018 W/cm2), short pulse (

Development of characterization methods and tools to address structural, electronic and optical properties of materials from the atomic-scale models. Characterization procedures to assess the reliability of the numerical models. Application of MDFT code to supercapacitor materials screening. Coupling of codes to increase accurateness of the computed properties. Modeling of materials at different lenght scales. Description of applications via continuous models. Model settings to design large scale simulations to address accurately macroscopic properties., H2020

The solubilization mechanism of lipid membranes in the presence of Triton X-100 (TX-100) is investigated at molecular resolution using molecular dynamics (MD) simulations. Thanks to the large time and length scales accessible by the hybrid particle-field formulation of the models employed here, the complex process of membrane solubilization has been studied, with the goal of verifying the three stage model reported in the literature. DPPC lipid bilayers and vesicles have been studied at different concentrations of the TX-100 detergent employing coarse grained (CG) models. Systems up to ∼600.000 beads, corresponding to more than 2 millions heavy atoms, have been simulated. Moreover, in order to clarify several experimental pieces of evidence, both slow and fast detergent partition scenarios have been investigated. Flat and curved (vesicles) lipid bilayer surfaces, interacting with TX-100, have been considered to study the curvature effects on the detergent partition rate in the membrane. Shape and conformational changes of mixed DPPC/TX-100 vesicles, as a function of TX-100 content, have also been studied. In particular, high curvature surfaces, corresponding to a higher local TX-100 content, promote a membrane rupture. In flat lipid surfaces, on the time scale simulated the detergent partition is almost absent, following a different pathway of the solubilization membrane mechanism. © 2017 the Owner Societies.

Optimization of all numerical codes ported in the infrastructure and used for supercapacitors, PV and batteries. The scope of deliverable D3.2 is to report the new advances in the field of materials for energy that comes from the search of new methodologies and models that could be more efficient on the new generation of computer hardware for exascale. In this respect, deliverable D3.2 is a transversal deliverable that report the new advances related to activities described in task T3.2, T3.3 and T3.4., H2020

Corrosion property of iron in high temperature stagnant liquid lead has been studied using molecular dynamics method. The method was used to predict the limit values of the injected oxygen into the liquid lead for maximum corrosion inhibition of iron. It is from experimental results, in order to inhibit the corrosion at possible lowest rate then a stable self-healing protective iron oxide layer should be developed at the surface of steel continuously. In this research we investigated the iron corrosion and it can be predicted that the protective oxide layer may be formed by injecting oxygen within the range of 5.35 × 10-2 wt% to 8.95 × 10-2 wt% (for observed temperature 750 C). The oxygen 5.35 × 10-2 wt% is the lower limit to prevent high dissolution of iron while the oxygen content of 8.95 × 10-2 wt% is the upper limit to avoid high precipitation of lead oxide. We also guess that effect of oxygen injection into liquid lead creates a thin oxygen barrier that separating the liquid lead and iron oxides from direct interaction. The iron oxides layer and oxygen barrier then may be regarded as double corrosion inhibition. © 2013 Elsevier Ltd. All rights reserved.

Doping of MgH2 with transition metals and their oxides is well-known procedure to improve its hydrogen (de) sorption properties, namely to lower the temperature of desorption and to achieve the kinetics speedup. In order to assess the influence Ti and TiO2 doping has on H mobility and to characterize structurally and electronically observed differences, MgH2-Mg interface doped with both Ti and TiO2 have been studied using ab-initio interface molecular dynamics and bulk calculations. Results suggest different mechanisms of MgH2 structure destabilization. The presence of dopants significantly stabilize MgH2-Mg interface, which is confirmed by work of adhesion computation. Calculated formation energies show that interface system with doped TiO2 is more stable. In terms of H mobility, molecular dynamics simulations confirm that Ti doping is more effective than TiO2 in lowering the desorption temperature. The mobility of hydrogen atoms close to dopant is much higher in the case of Ti than in the case of TiO2. Electronic structure characterization reveals that oxygen atoms with high electron affinity forms more pronounced ionic bonding with Ti and the other neighbor Mg atoms. This in turn cause a shorter Ti-H bonds in first coordination than in the case of Ti doping and further reduction of H atoms mobility. This is in accordance with molecular dynamics predictions. (C) 2016 Elsevier B.V. All rights reserved.