# Info about the hands-on courses

For the hands-on courses, participants are expected to bring
**their own laptops**. Prior to the summer school, all
participants should **install** an all-inclusive software
container (virtual machine) on their laptop. The software and
installation instructions are available **here**.

# QE-2019 Progam

Color code: (lecture-hall)Lecture(classroom)Hands-on

## DAY 0: Sunday, September 15 *(Basic introductory
lectures)*

14:00 − 14:45Anton Kokalj

A chemist view of bonding & a very informal intro to Bloch theorem: from molecules to solids and back14:45 − 15:00Coffee break15:00 − 18:00Stefano Baroni

Broad overview of theoretical methods: DFT, pseudopotentials, plane waves. Finite vs. infinite systems: supercells and k-points. Signal analysis: FFTs and the Nyqvist-Shannon theorem.Registration18:00 − 19:00Small welcome party: snacks & beverages

## DAY 1: Monday, September 16

8:00 − 8:50Registration & participant's computer setup check8:50 − 9:00Opening remarks & general instructions9:00 − 10:30Paolo Giannozzi and Pietro Delugas

Quantum ESPRESSO: overview and basic functionalities. The self-consistent cycle. PBC: supercells and k-point sampling.10:30 − 11:00Coffee break11:00 − 12:30Paolo Giannozzi and Pietro Delugas (contd).

Charge densities and potentials. Systems in 0-1-2-3D. Metals vs. insulators. Non-magnetic vs. magnetic systems.12:30 − 14:00Lunch14:00 − 14:30Participant’s computer setup check (contd).14:30 − 18:00Hands-on. Anton Kokalj, Pietro Delugas, Andrea Urru, Matic Poberžnik, Andrijana Solajić, Jelena Pešić

Installation. SCF + basic post-processing. XCrySDen, PWgui, QE-emacs-modes, PWTK (basics). Exercises.18:00 − 18:30Coffee break18:30 − 19:30Special guest lecture − Željko Šljivančanin

A short introduction to physics and chemistry at crystalline surfaces

A short introduction to physics and chemistry at crystalline surfaces

Željko ŠLJIVANČANIN

(Institute of Nuclear Sciences, Vinča, Serbia)

After a brief account of the most common ideal crystalline surfaces and their basic properties, I will describe the interaction of surfaces with atomic and molecular adsorbates. This will include modeling of simple chemical reactions at metal surfaces and the role played by structural defects. Then I will focus on graphene and efforts to modify its electronic properties via controlled hydrogenation.

Results from DFT calculations will be compared with those from the experiments, obtained using techniques such as scanning tunneling microscopy and temperature programmed desorption.

## DAY 2: Tuesday, September 17

9:00 − 10:30Paolo Giannozzi and Anton Kokalj

Forces, stresses, geometry optimisation. Chasing saddle points: the NEB method10:30 − 11:00Coffee break11:00 − 12:30Paolo Giannozzi

Advanced functionals: higher accuracy (hybrids), strongly correlated materials (DFT+U), weakly bound systems (van der Waals)12:30 − 14:00Lunch14:00 − 18:00Hands-on. Anton Kokalj, Iurii Timrov, Yusuf Shaidu, Matic Poberžnik, Matej Huš, Srdjan Stavrić

Optimizations, NEB, functionals. Automating the workflow with PWTK.18:00 − 18:30Coffee break18:30 − 19:30Special guest lecture − Iurii Timrov

First-principles quantum simulations of correlated materials using Hubbard-corrected density-functional (perturbation) theory

First-principles quantum simulations of correlated materials using Hubbard-corrected density-functional (perturbation) theory

Iurii TIMROV

(École Polytechnique Fédérale de Lausanne, Switzerland)

DFT+U and DFT+U+V are simple and powerful tools to model correlated systems containing partially-filled manifolds of localized d and f states [1]. However, the Hubbard U (on-site) and V (inter-site) parameters are often treated semi-empirically, which is a somewhat unsatisfactory approach. Conceptual and practical methods to determine e.g. the Hubbard U parameter from first principles have nevertheless been introduced long ago, based either on the constrained random-phase approximation or on linear-response theory [2]. Nonetheless, these approaches are often overlooked due to their cost and/or complexity. Here, we introduce a computationally inexpensive and straightforward approach to determine on-site U and inter-site V [3], hitherto obtained from the difference between bare and self-consistent inverse electronic susceptibilities evaluated from supercell calculations. By recasting these calculations in the language of density-functional perturbation theory (DFPT) [4] we remove the need of supercells, and allow for a fully automated determination of Hubbard parameters. Such developments open the way for deployment in high-throughput studies, while providing the community with a simple tool to calculate consistent values of U and V for any system at hand. The approach has been implemented in the Quantum ESPRESSO package [5] and is showcased with applications to selected transition-metal compounds. Lastly, we will discuss the effect of Hubbard corrections on the calculation of formation energies of systems with defects [6], phonons [7], and near-edge X-ray absorption fine structure [8].

References:

[1] V.I. Anisimov, J. Zaanen, O.K. Andersen, Phys. Rev. B 44, 943 (1991).

[2] M. Cococcioni and S. de Gironcoli, Phys. Rev. B 71, 035105 (2005).

[3] I. Timrov, N. Marzari and M. Cococcioni, Phys. Rev. B 98, 085127 (2018).

[4] S. Baroni, S. de Gironcoli, A. Dal Corso, P. Giannozzi, Rev. Mod. Phys. 73, 515 (2001).

[5] P. Giannozzi et al., J. Phys.: Condens. Matter 29, 465901 (2017).

[6] C. Ricca, I. Timrov, M. Cococcioni, N. Marzari, U. Aschauer, Phys. Rev. B 99, 094102 (2019).

[7] A. Floris, I. Timrov, B. Himmetoglu, S. de Gironcoli, N. Marzari, M. Cococcioni, in preparation.

[8] I. Timrov, P. Agrawal, S. Erat, A. Braun, M. Cococcioni, M. Calandra, N. Marzari, D. Passerone, in preparation.

## DAY 3: Wednesday, September 18

9:00 − 10:30Stefano Baroni

Density-functional perturbation theory: phonons10:30 − 11:00Coffee break11:00 − 12:30Iurii Timrov

Time-dependent density-functional (perturbation) theory: optical absorption and electron energy loss spectroscopies12:30 − 14:00Lunch14:00 − 18:00Hands-on. Iurii Timrov, Oscar Baseggio, Andrea Urru, Milan Jocić

(TD) DFPT18:00 − 18:30Coffee break18:30 − 21:00Elevator pitches + poster session (part I)

## DAY 4:Thursday, September 19

9:00 − 10:30Giovanni Pizzi

High-throughput computing with the AiiDA platform10:30 − 11:00Coffee break11:00 − 12:30Hands-on. Giovanni Pizzi, Nicola Spallanzani, Pietro Bonfà

Hands-on AiiDA12:30 − 14:00Lunch14:00 − 16:30Hands-on. Giovanni Pizzi, Nicola Spallanzani, Pietro Bonfà

Hands-on AiiDA16:30 − 17:00Coffee break17:00 − 18:00Special guest lecture − Dino Novko

Equilibrium and ultrafast vibrational dynamics from first principles

Equilibrium and ultrafast vibrational dynamics from first principles

Dino NOVKO

(Institute of Physics, Zagreb, Croatia)

Raman spectroscopy is a powerful and widely used technique for structural characterization and quality assessment of quasi-two-dimensional and layered materials. This tool under ultrafast transient conditions can as well be utilized to investigate the photo-induced phonon or nuclear dynamics. Here I present a theoretical framework based in first principles that is able to simulate both equilibrium and non-equilibrium dynamics of phonons in metallic systems. The main relaxation mechanism in this approach is coupling between thermalized/hot electrons and system phonons (i.e., nonadiabatic electron-phonon coupling). Using this general theory I explain the anomalous Raman spectrum of MgB2 and further reveal a laser-excited non-equilibrium dynamics of E2g phonon mode in this superconductor [1,2]. As another exciting example, I simulate Raman spectra of several single-layer transition metal dichalcogenides doped with field-effect technique [3] and show how the adiabatic Born-Oppenheimer approximation breaks down unexpectedly in these cases as well.

References:

[1] D. Novko, Phys. Rev. B 98, 041112(R) (2018)

[2] D. Novko, F. Caruso, C. Draxl, E. Cappelluti, arXiv:1904.03062, (2019)

[3] B. Chakraborty et al.,Phys. Rev. B 85, 161403(R) (2012)18:00 − 18:30Coffee break18:30 − 21:00Elevator pitches + poster session (part II)

## DAY 5: Friday, September 20

9:00 − 10:30Carlo Cavazzoni and Pietro Bonfà

Quantum ESPRESSO on HPC and GPU systems: parallelisation and hybrid architecture10:30 − 11:00Coffee break11:00 − 12:30Hands-on. Pietro Bonfà, Carlo Cavazzoni, Pietro Delugas, Drejc Kopač, Milan Jocić

Hands-on QE on HPC and GPU systems12:30 − 14:00Lunch14:00 − 16:30Hands-on. Pietro Bonfà, Carlo Cavazzoni, Pietro Delugas, Drejc Kopač, Milan Jocić

Hands-on QE on HPC and GPU systems16:30 − 16:45Break16:45 − 17:00Poster prize award & Closing remarks