During the past decade, computer simulations based on a quantum-mechanical description of the interactions between electrons and between electrons and atomic nuclei have developed an increasingly important impact on solid-state physics and chemistry and on materials science—promoting not only a deeper understanding, but also the possibility to contribute significantly to materials design for future technologies. This development is based on two important columns: (i) The improved description of electronic many-body effects within density-functional theory (DFT) and the upcoming post-DFT methods. (ii) The implementation of the new functionals and many-body techniques within highly efficient, stable, and versatile computer codes, which allow to exploit the potential of modern computer architectures. In this review, I discuss the implementation of various DFT functionals [local-density approximation (LDA), generalized gradient approximation (GGA), meta-GGA, hybrid functional mixing DFT, and exact (Hartree-Fock) exchange] and post-DFT approaches [DFT + U for strong electronic correlations in narrow bands, many-body perturbation theory (GW) for quasiparticle spectra, dynamical correlation effects via the adiabatic-connection fluctuation-dissipation theorem (AC-FDT)] in the Vienna ab initio simulation package VASP. VASP is a plane-wave all-electron code using the projector-augmented wave method to describe the electron-core interaction. The code uses fast iterative techniques for the diagonalization of the DFT Hamiltonian and allows to perform total-energy calculations and structural optimizations for systems with thousands of atoms and ab initio molecular dynamics simulations for ensembles with a few hundred atoms extending over several tens of ps. Applications in many different areas (structure and phase stability, mechanical and dynamical properties, liquids, glasses and quasicrystals, magnetism and magnetic nanostructures, semiconductors and insulators, surfaces, interfaces and thin films, chemical reactions, and catalysis) are reviewed. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008

Ab-initio simulations of materials using VASP: Density-functional theory and beyond.

Materials for hydrogen storage

Transparent conductors as solar energy materials: A panoramic review

https://uhra.herts.ac.uk/bitstream/handle/2299/11214/904970.pdf;sequence=2

A review of solar collectors and thermal energy storage in solar thermal applications

We give a general introduction to quantum phase transitions in strongly-correlated electron systems. These transitions which occur at zero temperature when a non-thermal parameter $g$ like pressure, chemical composition or magnetic field is tuned to a critical value are characterized by a dynamic exponent $z$ related to the energy and length scales $\Delta$ and $\xi$. Simple arguments based on an expansion to first order in the effective interaction allow to define an upper-critical dimension $D_{C}=4$ (where $D=d+z$ and $d$ is the spatial dimension) below which mean-field description is no longer valid. We emphasize the role of pertubative renormalization group (RG) approaches and self-consistent renormalized spin fluctuation (SCR-SF) theories to understand the quantum-classical crossover in the vicinity of the quantum critical point with generalization to the Kondo effect in heavy-fermion systems. Finally we quote some recent inelastic neutron scattering experiments performed on heavy-fermions which lead to unusual scaling law in $\omega /T$ for the dynamical spin susceptibility revealing critical local modes beyond the itinerant magnetism scheme and mention new attempts to describe this local quantum critical point.

https://arxiv.org/pdf/cond-mat/0102119.pdf

Quantum Phase Transitions

The pressure dependence of the superconducting transition temperature T c of Tl 2 Ba 2 Ca 2 Cu 3 O 10+ x (Tl-2223) has been measu red under pressures up to 13 GPa (130 kbar). At 4.2 GPa a maximum is observed with a T c of 133 K. This is the highest T c yet observed for any high- T c superconductor with the exception of the recently discovered mercury-based compound HgBa 2 Ca 2 Cu 3 O 8+ x (Hg-1223). Because of some structural differences between Tl-2223 and Hg-1223, a slightly higher maximum T c is predicted for Hg-1223. Both T c and its pressure dependence are discussed on the basis of a simple charge-transfer model.

Superconductivity at 133 K in Tl2Ba2Ca2Cu3O10+x under high pressure

Double layer formation in Mg–TM switchable mirrors (TM: Ni, Co, Fe)

Hydride Formation at Very High Hydrogen Pressure

Understanding diffusion of large solutes such as hydrogen and lithium in solids is of paramount importance for energy storage in metal hydrides and advanced batteries Due to its high gravimetric and volumetric densities, magnesium is a material of great potential for solid-state hydrogen storage However, the slow hydrogen diffusion kinetics and the deleterious blocking effect in magnesium have hampered its practical applications Here, we demonstrate fast lateral hydrogen diffusion in quasifree magnesium films without the blocking effect Massive concomitant lattice expansion leads to the formation of remarkable self-organized finger patterns extending over tens of micrometers Detailed visualization of diffusion fronts reveals that the fingers in these patterns follow locally the direction of hydrogen diffusion Thus, the streamlines of the diffusion process are self-recorded by means of the finger pattern By inclusion of fast hydrogen diffusion objects or local gaps, the resulting streamlines exhibit a clear analogy to optical rays in geometric optics The possibility to spatially manipulate hydrogen diffusion opens an avenue to build advanced hydrogen storage systems, cloaking and active plasmonic devices, as well as prototype systems for computational models

Self-recording and manipulation of fast long-range hydrogen diffusion in quasifree magnesium

Magnesium thin films covered with a layer of Pd absorb hydrogen at much higher pressures than bulk Mg. Such an effect was originally explained as a consequence of elastic clamping on Mg by the capping Pd layer. An alternative interpretation later suggested that the pressure increase could originate from simple alloying between Mg and Pd. Here we resolve this controversy by measuring the hydrogenation and dehydrogenation isotherms of Mg-Pd thin film alloys over a wide range of compositions. Our results disentangle the effects of elastic clamping and alloying and highlight the role of plastic deformations.

/pdf/elastic-versus-alloying-effects-in-mg-based-hydride-films-196ekry42z.pdf

R.P. Griessen

Papers

Superconductivity at 133 K in Tl2Ba2Ca2Cu3O10+x under high pressure

Double layer formation in Mg–TM switchable mirrors (TM: Ni, Co, Fe)

Hydride Formation at Very High Hydrogen Pressure

Self-recording and manipulation of fast long-range hydrogen diffusion in quasifree magnesium

Elastic versus Alloying Effects in Mg-Based Hydride Films