ELECTRONIC PROPERTIES AT THE NANOSCALE
The research line on “Electronic Properties at the Nanoscale” focuses on the electronic properties of solids, surfaces, nanostructures, and low-dimensional systems. Research within the line tackles the electronic properties both of ground and excited states of these systems. In particular, the electronic response of materials under different perturbations, i.e., different experimental probes (electromagnetic radiation, electrons, ions, etc.) is investigated. The way in which size, border, and dimensionality effects can change the properties of nanosized materials is under scrutiny.
Five research groups are included in this purely theoretical research line. The activity of all groups together covers the theoretical study of a wide range of materials, including both the microscopic and the mesoscopic scales, based on state-of-the-art methodologies. The list of research groups follows:
THE RESEARCH GROUPS
ELECTRONIC EXCITATIONS IN SURFACES AND NANOSTRUCTURES
The “Electronic Excitations in Surfaces and Nanostructures” group, mostly devoted to the theoretical study of electron dynamics in solids, surfaces, nanoscale systems and materials of technological interest. Furthermore, electronic and magnetic properties of materials are obtained using first principles methodologies. Electron dynamics in different systems is investigated, with particular emphasis on ultrafast processes and size effects. Advanced materials, such as topological insulators and cement-related systems are current targets of the group´s research.
Quantum Theory of Materials
The activity of the “Quantum Theory of Materials” group focuses on the first-principles calculation of materials properties and the development of new ab initio techniques. The group develops new theoretical methods to overcome the problems associated to standard theoretical approaches, specially, to describe with improved accuracy the quantum description of the electron-phonon and phonon-phonon interactions. These new techniques are applied to understand the electronic and vibrational properties of complex materials as well as to predict new compounds with interesting properties fully ab initio.
In the last years, the team has concentrated its efforts to study (i) high-temperature superconducting hydrogen-based compounds at high pressure, as well as hydrogen itself; (ii) thermoelectric and charge-density wave materials both in the bulk and the monolayer, aiming at characterizing their phase diagram and their transport properties; (iii) collective electronic excitations in metals; (iv) phonon polaritons; (v) optical lattices; and, finally, (vi) biophysical systems.
Aitor Bergara, associate professor at UPV/EHU, Jose María Pitarke, director of CIC nanoGUNE and university professor at UPV/EHU, and Ion Errea, associate professor at UPV/EHU, share interests and work as permanent researchers in this group, currently lead by Ion Errea. The later has gathered a team settled at CFM headquarters, constituting the new “Errea Lab”.
The Mesoscopic Physics group activity focuses on the theoretical aspects of quantum transport in nanostructures and mesoscopic systems. The main research covers various materials and structures, including metals, ferromagnets, semiconductors, superconductors, low dimensional systems, and topological matter. In addition to the theoretical activity, the group has a large network of experimental collaborators. In the past years, particular emphasis is placed on the following research objectives: (i) To develop theoretical tools for studying spin-dependent transport in hybrid systems with spin-orbit coupling, exchange fields, and superconductivity; (ii)To analyze the electronic heat transport at the nanoscale; (ii) To explore the possibility of using superconducting materials for sensing and detection; (iv) To design electronic and spintronics devices with new functionalities.
“Nano-bio Spectroscopy” group focuses on the theory and modelling of electronic and structural properties in condensed matter and on developing novel theoretical tools and computational codes to investigate the electronic response of solids and nanostructures to external electromagnetic fields. Present research activities include new developments within many-body theory and TDDFT. The theoretical description of optical spectroscopy, time-resolved spectroscopies, STM/STS and XAFS is also addressed. Methodological developments include novel techniques to calculate total energies and assessment and development of exchange-correlation functionals for TDDFT calculations and improvements on transport theory within the real-time TDDFT formalism.
SOUZA RESEARCH GROUP
“Souza’s research” group activity is focused on condensed-matter theory, using computational techniques to study the properties of materials from first principles. The group’s work often involves the development of new theoretical approaches and algorithms, and their application to problems of current interest, including methods to study insulators in finite electric field, as well as to construct localized Wannier orbitals for metals. Phenomena which arise from the interplay between the collective magnetic order in solids and the spin-orbit interaction inside the constituent atoms have been recently addressed as well.
CERAMIC AND CEMENT-BASED MATERIALS
Combining knowledge from different disciplines like solid-state physics, soft-matter physics, geochemistry and chemical engineering, the “Ceramic and Cement-based Materials” group focuses on the computational design and synthesis of new ceramic and cement based materials with lower CO2 fingerprint. Among its different lines of research, they are worth mentioning:
- The use of atomistic and colloidal simulations to study the structure and properties of materials
- The implementation of new hydrothermal and supercritical fluids (SCF) technologies for the ultra-fast synthesis of ceramic nanoparticles
- The development of new sintering methodologies through the use of autoclaves or microwaves that allow notable energy saving and a drastic reduction of CO2 emissions
- Development of energy storage solutions based on cement-based materials, including both chemical storage (batteries) and thermal storage systems (TES) applications.
THEORY OF ELECTRONIC AND OPTICAL EXCITATIONS IN SOLIDS
The group’s research focuses on material properties of current interest, including (but not limited to) nonlinear optical response of semiconductors, collective electronic excitations, and magnetic behavior of low-dimensional systems like single adatoms. For the first-principles characterization of these systems we generally make use of state-of-the-art software packages that implement the density functional theory. For the analysis of the more exotic properties we develop our own algorithms and theoretical approaches, which often make use of k-dot-p and tight-binding models.
Several computing clusters at the CFM and other institutions (such as DIPC) under collaborative research. Several scientific codes for ab initio calculations (DFT based on plane waves and local orbitals, quantum chemistry), as well as other computational and graphic packages.
Development of scientific software for ab initio calculations, including time-dependent propagation, electromagnetic and optical response, as well as for other methodologies. Development of packages freely distributed to the scientific community (e.g., OCTOPUS for time-dependent density functional theory calculations).