Gunnar K. Pálsson

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Semiconductor heterostructures are the fundamental platform for many important device applications such as lasers, light-emitting diodes, solar cells, and high-electron-mobility transistors. Analogous to traditional heterostructures, layered transition metal dichalcogenide heterostructures can be designed and built by assembling individual single layers(More)
We propose a cellular version of dynamical mean field theory which gives a natural generalization of its original single-site construction and is formulated in different sets of variables. We incorporate a possible nonorthogonality of the tight-binding basis set and prove that the resulting equations lead to manifestly causal self-energies. Dynamical mean(More)
Mg-Ti alloys have uncommon optical and hydrogen absorbing properties, originating from a " spinodal-like " microstructure with a small degree of chemical short-range order in the atomic distribution. In the present study we artificially engineer short-range order by depositing Pd-capped Mg/Ti multilayers with different periodici-ties. Notwithstanding the(More)
We present a method to calculate optical properties of strongly correlated systems. It is based on dynamical mean-field theory and it uses as an input realistic electronic structure obtained by local density-functional calculations. Numerically, tractable equations for optical conductivity, which show a correct noninteracting limit, are derived.(More)
The chemical diffusion coefficient of hydrogen in a 50 nm thin film of vanadium (0 0 1) is measured as a function of concentration and temperature, well above the known phase boundaries. Arrhenius analysis of the tracer diffusion constants reveal large changes in the activation energy with concentration: from 0.10 at 0.05 in H V(-1) to 0.5 eV at 0.2 in H(More)
Because of its light weight and small size, hydrogen exhibits one of the fastest diffusion rates in solid materials, comparable to the diffusion rate of liquid water molecules at room temperature. The diffusion rate is determined by an intricate combination of quantum effects and dynamic interplay with the displacement of host atoms that is still only(More)
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