Introduction

Welcome to the pARTn Hackathon!

The hackathon will be held April 1st -- 3rd 2026, at IRB.

Register here.

What is this?

ARTn algorithm

The Activation-Relaxation Technique nouveau (ARTn) is an algorithm for open-ended search of saddle points of Potential Energy Surfaces (PES) of atomic systems.

ARTn uses the information of local curvature of the PES, to determine a direction of lowest negative curvature. The atomic system is pushed uphill along that direction, while minimized in all other directions. After a number of such steps, the system converges to a saddle point of the PES.

Plugin-ARTn implementation

The plugin-ARTn (pARTn) is an implementation of ARTn as a plugin, i.e. an explicitly external routine to be used by an Energy/Force engine.

Git repository, and online documentation are available.

pARTn is written in modern Fortran, and is interoperable with C through the intrinsic iso_c_binding module, and bind(C) directives. The interoperability with C is also used to define a python interface pypARTn, and can be used to call pARTn from other languages, i.e. lua.

Hackathon!

The idea of this hackathon is to go into the very details of pARTn, and attempt to address some issues, or improve on some specifics, or even just apply the code to a particular set of problems.

The first day there will be some talks, going from fairly broad introductory, to narrowing down to the details of pARTn algorithm, and code. Then, some potential project topics will be presented, which can be picked up by any working group, or just serve as foundation ideas for other projects.

On the second and third day, the participants will split into voluntary working groups, each addressing their own chosen problem/project, or any other problem/project they could come up with.

Any potentially interesting work can continue developing after the event, possibly turning into a joint publication.

Project ideas

Currently some ideas for problems/projects to address are:

  • defining benchmarks (i.e. OptBench integration, expansion of systems, etc.);
  • interfacing into eOn;
  • can the code execute when on GPU? and/or how to make that possible?
  • addressing the soft modes appearing from Lanczos diagonalization: detection, and removal. Possible algorithm branching;
  • general way to add custom "modifiers": such as freezing atoms only during particular block of ARTn, etc.
  • application to any system a participant might bring up;
  • ...

Any other project ideas are welcome!

Program

Day 1:

  • 12:00 Welcome, thanks for coming! (Miha)
  • Introduction to Transition State Theory, what is a PES, and why saddle points? (Alejandro Pena Torres)
  • NEB and Dimer within scope of ML; what to watch out for, and lessons already learned (Rohit Goswami)
  • The ARTn algorithm (Matic Poberznik)
  • 14:30 coffee break and posters (1h)
  • The various engine interfaces to pARTn: details (Nicolas Salles)
  • pARTn source code details & overview of possible work projects/problems (Miha)
  • Installation party: It's a pARTy! Let's compile pARTn together! (Miha)

Day 2:

  • 9:30 Overview of possible work projects; have any new ideas turned up since yesterday?
  • Decide how to split into workgroups, define workload
  • hack hack
  • 12:00 lunch
  • hack hack hack

Day 3:

  • 9:30 10min morning update
  • hack hack
  • 12:00 lunch
  • hack hack hack
  • round table: update from groups, and how/when/where to continue?

Location

Institute Ruđer Bošković (IRB), address: Bijenička 54, 10000 Zagreb, Croatia

Website: https://www.irb.hr/eng

Getting to IRB

From Kaptol, buses:

  106, 201, 203, 226, 238

From Kvaternikov trg, buses:

  • 201;
  • 204 (stop Horvatovac PMF, walk 3min);
  • 207 (stop Srebrnjak, walk 3min)

Tram/bus tickets

Same ticket for trams and buses. Cost 0.53 EUR for single ticket. Buy at any kiosk/tobacco shop, or install the app Moj ZET and pay by scanning QR codes in the tram/bus.

Registration

The event is free of charge, however the number of participants is limited.

To register, please fill out the form.

Participants

Organizer

* Miha Gunde              (Institute Ruđer Bošković, Zagreb, Croatia);
  contact: mgunde at irb dot hr

Invited

* Matic Poberžnik         (Institute Jožef Stefan, Ljubljana, Slovenia);
* Antoine Jay             (LAAS-CNRS, Toulouse, France);
* Nicolas Salles          (CNR-IOM/SISSA, Trieste, Italy);
* Layla Martin-Samos      (CNR-IOM/SISSA, Trieste, Italy);
* Gabriela Herrero-Saboya (CNR-IOM/SISSA, Trieste, Italy);
* Rohit Goswami           (LabCOSMO-EPFL, Lausanne, Switzerland);
* Alejandro Peña Torres   (University of Iceland, Reykjavík, Iceland);

Participants

* Liam Smyth              (Queen’s University, Kingston, Ontario, Canada);
* Eugène Sanscartier      (Université de Montréal, Montréal, Québec, Canada);
* Ivor Lončarić           (Institute Ruđer Bošković, Zagreb, Croatia);
* Ivana Podlipnik         (Institute Jožef Stefan, Ljubljana, Slovenia);
* Arezou Farajollahzadeh  (University of Zanjan, Zanjan, Iran);
* Joe Rayner              (Institute Ruđer Bošković, Zagreb, Croatia);
* Berislav Perić          (Institute Ruđer Bošković, Zagreb, Croatia);
* Alejandro Neyra         (CNR-IOM/SISSA, Trieste, Italy);