Mohammad Saeed Bahramy

Chemical engineering of prehydrogenated C and BN-sheets by Li: Application in hydrogen storage

Our first-principles calculations show that if the hydrogen atoms on one of the faces of a graphane sheet (prehydrogenated graphene) are substituted with Li atoms, the resulting monolayer attains a good hydrogen storage capacity of around 3.8 wt % close to the revised Department of Energy (DOE) target. It is observed that Li atoms are strongly hybridized with the monolayer and donate their electrons to the substrate such that their binding energy to the surface becomes around −3.27 eV, which is far larger than the cohesive energy of Li in its metal bulk structure. It indicates that Li atoms on the monolayer are not aggregated or clusterized at high doping concentration and high temperature. Our calculation shows that the binding energy of H2 molecules with the monolayer surface is around −0.1 eV resulting from the electrostatic interaction of the polarized charge of hydrogen molecules with the induced electric field by positively charged Li atoms. Similarly, we have examined the hydrogen storage capacity ...

High-pressure phases of hydrogen cyanide: formation of hydrogenated carbon nitride polymers and layers and their electronic properties

We have performed a set of first-principles simulations to consider the possible phase transitions in molecular crystals of HCN under high pressure. Our calculations reveal several transition paths from the orthorhombic phase to tetragonal and then to triclinic phases. The transitions from the orthorhombic to the tetragonal phases are of the second order, whereas those from the tetragonal to the triclinic phases turn out to be of the first-order type and characterized by an abrupt decrease in volume. Our calculations show that, by adjustment of the temperature and pressure of the HCN molecular crystal, novel layered and polymeric crystals with insulating, semiconducting or metallic properties can be found. Based on our simulation results, two different crystal formation mechanisms are deduced. The stabilities of the predicted structures at ambient pressure are further assessed by performing phonon or MD simulations. In addition, the electron transport properties of the predicted polymers are obtained using the non-equilibrium Greens function technique combined with density functional theory. The results show that the polymers have metallic-like I-V characteristics.

Calculations of spin-induced transport in ferromagnets

Based on first-principles density functional calculations, a general approach for determining and analyzing the degree of spin polarization

Optoelectronic and magnetic properties of Mn-doped indium tin oxide: A first-principles study

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First-principles study of structural stability, magnetism, and hyperfine coupling in hydrogen clusters adsorbed on graphene

in ferromagnets is presented. The approach employs the so-called tetrahedron method to evaluate the Fermi surface integrations of

Geometrical indications of adsorbed hydrogen atoms on graphite producing star and ellipsoidal like features in scanning tunneling microscopy images: Ab initio study

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First-principles calculations of hyperfine parameters with the all-electron mixed-basis method

in both ballistic and diffusive regimes. The validity of the method is examined by comparing the calculated

Pseudopotential hyperfine calculations through perturbative core-level polarization

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First-Principles Calculations of Hyperfine Structure in M-doped Si16H16 Fullerene Cages (M=Cr, Mn, and Fe)

values for Fe and Ni with the experiment. The method is shown to yield highly accurate results with minimal computational effort. Within our approach, it is also possible to systematically analyze the contributions of various types of electronic states to the spin-induced transport. As a case study, the transport properties of the soft-ferromagnet

Magnetic phase stability and spin-dependent transport in CeNi4M (M=Sc, Ti, V, Cr, Mn, Fe, and Co) : First-principles study

\mathrm{Ce}\mathrm{Mn}{\mathrm{Ni}}_{4}