Continued Support — Advanced Simulation Methods. This project focuses on the integration of methods developed around correlated materials and on devices already started in phase II. The efforts are spread across three sub-projects: Accurate open source simulation framework for correlated materials; Correlations in realistic systems; and Electrical, thermal, and optical effects in 2D nanodevices.
In the first two phases of MARVEL, substantial resources were invested into the development of an accurate and parameter-free ab initio simulation method for correlated electron material. This class of materials exhibits some of the most remarkable phenomenon found in condensed matter systems, but their strongly correlated nature requires a theoretical treatment that goes beyond density functional theory (DFT) or weak-coupling perturbation theory. The new approach is based on the combination of dynamical meanfield theory (DMFT) with the GW method and has been successfully tested. The goal for phase III is to turn this complex simulation framework into an efficient, easily usable and well-documented open source code that can handle O(10) correlated orbitals per site, treat several sites in a unit cell, and read ab initio input from different widely used codes such as FLEUR or Quantum ESPRESSO.
Simulations of atomistic models as close as possible to reality are key to success in meeting the challenge of realizing atomically precise bottom-up synthesis of graphene-derived structures, themselves opening up the way to the design of carbon-based nanomaterials and devices. A specific challenges in this regard is the lack of efficient and reliable methods capable of describing electron transport in reduced-size systems where screening effects play a fundamental role. The main objective in phase III is to develop a computational tool for calculating the conductance in these regimes.
Scaling down the dimensions of electronic devices to the sub-nanometer range not only influences their electronic transport properties, but also their electron-phonon and light-matter interactions. Being able to accurately model them has become critical to the design of ultra-scaled field-effect transistors (FET), thermoelectric nano-generators (TEG), and highly efficient photovoltaic (PV) cells. The objective of this project is therefore to set up an environment to automatically generate the required parameters and apply them to the modeling of nanodevices, for example ultra-scaled transistors with various 2D channel materials. The work will involve collaborations with experimental groups at ETHZ, EPFL, and Empa.
The project is led by Philipp Werner, Daniele Passerone and Mathieu Luisier.