Joint Physics Dept - MtSE Seminar

May 11th, Thursday (**SPECIAL DAY**)

First Principles Calculations of Strongly Correlated Materials: A Variational Perspective

Dr. Nicola Lanatà

National High Magnetic Field Laboratory, Florida State University

(Theoretical Condensed Matter Physics, Host: Ken Ahn)

**SPECIAL TIME: 2:45 pm - 3:45 pm with 2:30 pm tea time

Room: ECE 202

Strongly Correlated Materials are characterized by the presence of localized d or f electrons near the Fermi level. The emergence of the corresponding atomic energy scales makes it impossible to model the electronic structure of this broad class of systems in terms of free electron waves in a periodic potential (band theory). In turn, the resulting competing mechanisms can give rise to a whole variety of phases and collective phenomena that do not exist in weakly correlated systems, such as high-T_c superconductivity, Mott transition, magnetism, mass renormalization, quasiparticles, Kondo physics. A key challenge in modern Condensed Matter consists in understanding and describing quantitatively the physics governing Strongly Correlated Materials based on the properties of the underlying elementary constituents. This is also essential in Materials Science, as theory and simulation can contribute substantially to accelerate the discovery process of new materials with functional properties. In order to achieve these goals, the development of appropriate methods sufficiently accurate to make direct connection with the experiments and, at the same time, sufficiently simple to enable us to capture the main physical effects emerging at the many body scale, is an absolute necessity. In this talk I will briefly introduce some of the theoretical ideas and computational approaches that I have developed in the past few years [1,2]. As an example, I will present first principles calculations of elemental Cerium [3,4], which reproduce very accurately the experiments and enable us to explain theoretically the γ-α transition in this material -- employing also ideas from quantum information theory to identify the key physical effects at play in the system [5].

[1] Lanatà et al., Phys.Rev.Lett. 118, 126401 (2017); [2] Lanatà et al., Phys.Rev.X 5, 011008 (2015); [3] Lanatà et al., Phys.Rev.B (Rapid Comm.) 90, 161104(R) (2014); [4] Lanatà et al., Phys.Rev.Lett. 111, 196801 (2013); [5] Lanatà et al., Phys.Rev.Lett. 113, 036402 (2014).

Biography: Nicola Lanatà obtained PhD in “Theory and Numerical Simulation in Condensed Matter Systems” at the International School for Advanced Studies (Italy) in 2009, under the supervision of Prof. Fabrizio. He subsequently worked for two years as a postdoc at Gothenburg U.(Sweden), and for another three years at Rutgers U. under the supervision of Prof. Kotliar. In 2015, he joined the National High Magnetic Field Laboratory as Dirac Postdoctoral Fellow. His research activity has been mainly concerned with the physics of Strongly Correlated Materials, Materials Science and the development of new theoretical and computational methods, including an open-source code awarded with the “Ames Laboratory Patent Award” in 2014.