Anharmonicity and electron-phonon interactions have been central for decades in condensed matter research. As we progress in developing robust computational methods to address anharmonicity and electron-phonon coupling individually, there is an increasing need to integrate both on a unified approach. In this talk, Dr Zacharias will discuss how the anharmonic special displacement method (ASDM) can serve as a simple and efficient tool towards this perspective. In particular, he will show that the ASDM removes the need for extensive sampling of the nuclear configuration space performed in Monte Carlo or Molecular Dynamics simulations. In the ASDM, only a handful of configurations suffice to capture both the effective temperature-dependent potential energy surface and its interplay with the electronic structure, streamlining the process with efficiency.

 

Dr Zacharias will demonstrate how this method can interpret challenging thermal and nonequilibrium phenomena observed in metal halide perovskites, which are at the forefront of materials research for next-generation photovoltaics. Finally, he will discuss how Machine-Learning Force Fields can offer an ideal platform to accelerate large-scale ASDM calculations of complex electron-phonon interactions in polymorphous systems.

 

Dr. Marios Zacharias is currently an MSCA postdoctoral researcher at FOTON Institute, INSA, Rennes working with Prof. Jacky Even in the field of halide perovskites. He earned his Ph.D. in Materials Science at Oxford University, United Kingdom (2017) and held a post-doctoral appointment at Oxford University (2018), under the supervision of Prof. F. Giustino. In 2019, he joined the NOMAD laboratory of Prof. M. Scheffler at Fritz Haber Institute in Berlin. From 2020 to 2021, he moved to the Cyprus University of Technology and led the simulation group of RUNMS of Prof. P. C. Kelires.

His research interests focus on electronic structure theory and the development of new first-principles techniques for the accurate and efficient description of anharmonicity, electron-phonon, and vibronic physics of condensed matter systems. He is the developer of the software package EPW/ZG in Quantum Espresso. He has developed the special displacement method (SDM) for electronic structure calculations at finite temperatures. Marios has also introduced an approach for the calculation of multiphonon diffuse scattering allowing for the interpretation of thermal and ultrafast phenomena in solids.

He is currently working on the efficient treatment of anharmonicity and polymorphism in halide and oxide perovskites.