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  2. QUEST – Multireference quasiparticles for strong correlation

Research project selected under the 2019 call for proposals

Principal Investigator : Pina ROMANIELLO

Involved Teams :

  • LPT / Agrégats
  • LPCQ / Methods and tools of quantum Chemistry, GMO

Type of project : Collaborative Project

Date (start/end) : 2019 – 2022

Figure 1. Phase diagram of V2O3. The first-order vertical line separating the blue insulating region from the red metallic one terminates in a critical point at about 400 K. Below the Néel temperature line the structure is monoclinic while above, irrespective of the side of the metal-insulator transition, the material has a corundum crystal structure.

This project proposes to tackle one of the grand challenges of physics and chemistry, i.e. the description of strong electron correlation from first principles. Strong correlation effects play a central role in most of the recently discovered innovative functional materials. In particular here we focus on systems at the verge of a metal-insulator transition [1] which display a whelm of exotic properties due to a great sensitivity to external parameters (see, as an example, the phase diagrams of V2O3 in Fig. 1). For such systems, the electronic wave function is inherently of multi-reference character, i.e. it requires more than one electronic configuration to be accurately described. Up to now, very little has been done in that direction. Here, we propose to tackle this problem by combining two different, yet complementary, approaches: a condensed matter description based on quasi-particles (expert: Pina Romaniello) [2] and a quantum chemistry description based on multi-reference wave functions (expert: Pierre-Francois Loos) [3], hence contemplating the concept of “multi-reference quasi-particles”.

References

[1] N. F. Mott, Rev. Mod. Phys. 40, 677 (1968)

[2] (a) P. Romaniello, F. Bechstedt, and L. Reining, Phys. Rev. B 85,155131 (2012); (b) S. Di Sabatino, J. A. Berger, L. Reining, and P. Romaniello, Phys. Rev. B 94, 155141 (2016); (c) S. Di Sabatino, J. A. Berger, and P. Romaniello, submitted to J. Chem. Theory Comput., arXiv:1903.09514

[3] (a) Y. Garniron, A. Scemama, P. F. Loos, and M. Caffarel, J. Chem. Phys. 147, 034101 (2017); (b) Y. Garniron, A. Scemama, E. Giner, M. Caffarel, and P. F. Loos, ibid. 149, 064103 (2018); (c) P. F. Loos, A. Scemama, A. Blondel, Y. Garniron, M. Caffarel, and D. Jacquemin, J. Chem. Theory Comput. 14, 4360 (2018); (d) A. Scemama, Y. Garniron, M. Caffarel, and P. F. Loos, ibid. 14, 1395 (2018); (e) J. Chem. Phys. 149, 034108 (2018)