Programme

Electronic structure methods (DFT and beyond)

When tackling the problem of interacting many-electron systems, Density Functional Theory (DFT) [1,2] has consistently proven to be the most widely used tool [3] due to its computational feasibility and great success in describing ground-state properties. Despite being an exact theory, DFT relies on approximations for the exchange and correlation functional, which is the key element both in the success and pitfalls of DFT. On the one hand, simple local and semi-local approximations [4] have been shown to accurately reproduce structural and geometrical properties. However, on the other hand, DFT seriously underestimates the energy barriers in chemical reactions, band gaps of solids and dissociation energies of molecular ions to mention a few. This section will be devoted to new developments in DFT and other electronic structure methods which allow us to overcome these and other shortcomings. The section will focus particularly on the spectroscopic properties of materials.

[1] P. Hohenberg, and W. Kohn, Phys. Rev. 136, B864 (1964).
[2] W. Kohn, and L. J. Sham, Phys. Rev. 140, A1133 (1965).
[3] R. Van Noorden, B. Maher, and R. Nuzzo, Nat. News 514, 7524 (2014).
[4] J. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 18 (1996).

Invited speakers: Nicola Colonna

Strongly correlated systems

The strongly correlated systems exhibit phenomena which cannot be explained using standard band theory. In these compounds, the electronic interactions play a crucial role in defining a system's properties. Therefore, the correct description of the electronic correlations requires adequate methods such as dynamical mean field theory (DMFT) [1], slave particle approaches [2], Quantum Monte Carlo [3] and others. Strongly correlated systems are a wide class of materials including Mott insulators, heavy fermion compounds [4] and high-Tc unconventional superconductors. The latter, in particular, have been topic of debate and extensive study, with the most prominent compounds being cuprates [4] and iron-based superconductors [5]. Overall, the investigation of such systems have attracted considerable research interest due to related novel unusual phenomena and the fact that they constitute a great playground for the study of complicated many-body processes.

[1] A. Georges et al., Rev. Mod. Phys. 68, 13 (1996).
[2] G. Kotliar, A. Ruckenstein, Phys. Rev. Lett. 57, 1362 (1986). L. de’ Medici, et al.,Phys. Rev. B 72, 205124 (2005). R. Yu, Q. Si Phys. Rev. B 86, 085104 (2012).
[3] E. Dagotto, Rev. Mod. Phys. 66, 763 (1994). G. Kotliar, S. Y. Savrasov, K. Haule, V. S. Oudovenko, O. Parcollet, and C. A. Marianetti, Rev. Mod. Phys. 78, 865 (2006).
[4] J.G. Bednorz, K.A. Muller, Zeitschrift fur Physik B Condensed Matter 64, 189 (1986). P.W. Anderson, The theory of superconductivity in the high-Tc cuprate superconductors Vol. 446, Princeton University Press, Princeton (1997).
[5] Y. Kamihara et al., J. Am. Chem. Soc. 128, 10012 (2006).

Invited speakers: Anna Galler, Yaroslav Kvashnin

Vibrational properties of materials

Most ab initio approaches assume the frozen lattice approximation, where one supposes that ions keep their positions fixed. However, the presence of vibrational degrees of freedom often gives a fundamental contribution to many physical quantities such as thermal conductivity, electrical resistivity, and optical absorption. Therefore, one has to find a way to properly account for the nuclear motion in the calculation. This can be done, at a first level of accuracy, with the harmonic approximation for phonons. However, this approach is valid only in the approximations of small nuclear displacements, and when strongly anharmonic systems are considered (for example in the case of structural phase transitions), one must search for more sophisticated approaches [1,2]. This session will be devoted to researchers who want to present their work on the vibrational properties of materials, in particular for those works which focus on the influence of vibrational degrees of freedom on spectroscopic quantities.

[1] A. Dewandre et al., Phys. Rev. Lett. 117, 276601 (2016).
[2] G. A. Ribeiro et al, Phys. Rev. B 97, 014306 (2018).

Invited speakers: Konstanze Hahn, Fulvio Paleari

Optical properties of materials

The optical measurements are a powerful, cheap, and non-destructive tool to acquire the electronic structure of materials. The knowledge of accurate theoretical spectra can be used as a reference and compared within experiments in order to characterize, for example, the purity of a sample. Moreover, the capability to calculate reliable absorption spectra from first principles plays a prominent role in the design of materials for several technological applications. Bearing these reasons in mind, developing accurate methods for optical first-principle calculations is a goal of primary importance. Unfortunately, it is a formidably challenging problem, mainly due to the difficulty of properly accounting for the electron-hole interaction. In Time-Dependent Density Functional Theory (TDDFT) [1] - which is, in principle, an exact theory - accurate approximations for the exchange-correlation kernel are still lacking [2]. On the other hand, the Bethe Salpeter equation (BSE) [3], which is currently at the forefront in calculations of absorption spectra [2], allows for the description of correlation effects only at the cost of a considerable computational effort. In this session, we will host researchers working both on the development of new methods and on more phenomenological aspects of these subjects (i.e., the properties of new materials).

[1] Erich Runge and E. K. U. Gross, Phys. Rev. Lett. 52, 997 (1984).
[2] Giovanni Onida, et al, Rev. Mod. Phys. 74 , 601 (2002).
[3] W. Hanke and L. J. Sham, Phys. Rev. B 21, 4656 (1980).

Invited speakers: Nicolas Tancogne-Dejean

Multiscale modelling

Density Functional Theory (DFT) is the main electronic structure method which is used for the simulation of materials, catalysis and biological systems. However, systems containing thousands of atoms as well as the long time scale dynamics are still not tractable within the conventional Kohn-Sham theory. This session will be devoted to the methodology and applications of the theories which allows one to overcome size and time-scale problems in DFT. This includes but is not limited to rate theory [1], hybrid quantum mechanical/molecular mechanical [2] and machine learning based approaches [3].

[1] B. Peters, Reaction Rate Theory and Rare Events Simulations (2017).
[2] A. Warshel, and M. Levitt, J. Mol. Biol. 103, 227 (1976).
[3] A. P. Bartók, M. C. Payne, R. Kondor, and G. Csányi, Phys. Rev. Lett. 104, 136403 (2010).

Invited speakers: Bingqing Cheng

Detailed Programme:

Monday

09:00 - 10:00 Nicola Colonna, "Spectral properties of molecules and solids from a functional approach."

10:00 - 10:20 Dario A. Leon, "Frequency dependence in GW made simple using a multi-pole approximation."

10:40 - 11:00 T. Chiarotti, "Solving the Dyson equation via the algorithmic inversion."

11:00 - 11:20 S. Vacondio, "HIgher-order many-body perturbation theory benchmarked on atoms."

11:20 - 11:40 L. Caputo, "First-principles electronic and structural properties of BNC nanomaterials."

11:40 - 12:00 N Zibouche, "A GW study of dielectric screening effects on the quasiparticle properties of monolayer MoS2."

14:00 - 15:00 Yaroslav Kvashin, "Modelling magnetism and strong correlations in real materials."

15:00 - 15:20 A. Lorenzo Mariano, "A density-corrected DFT scheme applied to the calculation of spin-state energetics."

15:40 - 16:00 G F von Rudorff, "Alchemical Perturbation Density Functional Theory: Scaling with chemical space."

16:00 - 16:20 Ayoub Aouina, "New approximation to the exchange correlation potential from connector theory, application to the density of silicon and sodium chloride."

16:20 - 16:40. G. Riva, "Photoemission spectroscopy from the three-body Green’s function."

Tuesday

09:00 - 10:00 Konstanze Hahn, "Calculation of phonon dispersion and thermal conductivity in various systems using DFT."

10:00 - 10:20 R. Claes, "Phonon-limited carrier mobility in semiconductors from first principles."

10:40 - 11:00 A. El Sahili, "Perturbation theory beyond GW introduction to the GW-GWGWG approximation."

11:00 - 11:20 I. Maity, "Chiral valley phonons and flat phonon bands in moiré patterns of WSe2"

11:20 - 11:40 N Rivano, "Polar optical phonons in one-dimensional materials."

11:40 - 12:00 K Lively, "Simulating Vibronic Spectra without Born-Oppenheimer Surfaces."

14:00 - 15:00 Fulvio Paleari, "The problem of exciton-phonon interaction."

15:00 - 15:20 Francesco Libbi, "Phonon-assisted luminescence in defect centers from many body perturbation theory: the boron vacancy in 2D hBN"

15:40 - 16:00 S. Postorino, "Direct and indirect excitons in monolayer and bilayer Molibdenum Ditelluride."

16:00 - 16:20 J. Bouquiaux, "First-principle study of the luminescence spectrum of Eu2+, doped phosphors."

Wednesday

09:00 - 10:00 Nicolas Tancogne-Dejean, "Advances in strong-field and ultrafast op5cal spectroscopies of solids."

10:00 - 10:20 R. Sinha-Roy, "Orbital Magnetism in Nanoparticles from Real-Time TDDFT."

10:40 - 11:00 V. Gorelov, "Ab-inition investigation of electronic excitations in bulk V2O5."

11:00 - 11:20 L. Adamska, "Investigating dynamical Franz—Keldysh effects and beyond in bulk Germanium via TDDFT."

11:20 - 11:40 Miki Bonacci, "Exciton Effects in Graphene-like C3N."

11:40 - 12:00 P. Lechifflart, "Optical properties of strained hexagonal Boron Nitride."

14:00 - 14:20 S. Rost, "Electron energy loss spectroscopy (EELS) for 2D materials."

14:20 - 14:40 P. M.M.C. de Melo "Optical properties of defect centers on 2D transition metal dichalcogenides."

14:40 - 15:00 Kalyani Chordiya "Real Time Observation of Correlated Electrons Response to Photo-Ionization."

15:00 - 15:20 R. Reho, "Quasi-equilibrium states in heterobilayers of transition metal dichalcogenides."

15:40 - 16:10 Nicole Holzmann, "Quantum Chemistry on Quantum Computers – A Startup through the Looking Glass."

16:10 - 16:40 Maja Berović, TBA.

Thursday

09:00 - 10:00 Anna Galler, "Ab-initio calculations for materials with correlated 3d and 4f shells."

10:00 - 10:20 Miguel Escobar Azor, "Wigner localization in one, two and three dimensions: an ab initio approach."

10:40 - 11:00 Maria Chatzieleftheriou, "First-order in the Mott transition induces a quantum critical point at finite doping."

11:00 - 11:20 S. Sesti, "Excitonic vs Mott insulator in carbon nanotubes: a proposed experimental test."

11:20 - 11:40 R. Orlando, "Exploring new exchange-correlation kernel in the Bethe - Salpeter equation: a study on the Hubbard dimer."

11:40 - 12:00 A. Guandalini, "Efficient GW calculations in two dimensional through the interpolation of the screened potential."

Friday

09:00 - 10:00 Bingqing Cheng, "Predicting material properties with the help of machine learning."

10:00 - 10:20 Loris Ercole, "Doping solid-state electrolytes: a pinball model study."

10:40 - 11:00 Massimiliano Comin, "Embedded many-body petrubation theory for complex molecular systems: fundamentals and applications to doped semiconducting polymers."

11:00 - 11:20 Pierre-Paul De Breuck, "Materials property prediction for limited datasets and bias-imbalance in data-driven materials science."

11:20 - 11:40 Thomas E. Baker, "Lanczos recursion on a quantum computer for the Green’s function and wavefunctions."

Book of Abstracts.

You can download the book of abstracts here: