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*Amazing Community of Contributors*

- Beginning of the Code: Volker Blum, Karsten Reuter, Matthias Scheffler at Fritz Haber Institute, 2004
- Since then: Hundreds of individuals, without whom FHI-aims would not exist
- Direct contributors to FHI-aims: ~150

- FHI-aims is licensed through MS1P e.V. - a registered nonprofit supporting basic science
- User registration and code download at fhi-aims.org
- Primary communication platform: Slack Workspace
- Code developement at the FHI-aims GitLab including stable versions, issue tracker, wiki, and build instructions

*Vision:*

Quantum mechanics based simulations of molecules, materials and their properties without a priori precision and accuracy limitations

**Numeric atom-centered basis functions**

for an accurate representation of occupied orbitals and densities

*Algorithmic choices and priorities*

- All-electron, full potential
- Non-periodic and periodic systems on equal footing
- Scalability to large systems (thousands of atoms) without precision limitations
- Seamless scalability from laptop to massively parallel HPC architectures
- Density functional theory and correlated methods (RPA, GW, ...)

↓

$u_i(r)$: Localized radial function. Flexible choice - “Anything you like.”

Solution to the free atom radial Schrödinger equation:

\[\begin{aligned} \left[ - \frac{1}{2} \frac{\text{d}^2}{\text{d}r^2} + \frac{l(l+1)}{r^2} + v_i(r) +v_\text{cut}(r) \right] u_i(r) = \epsilon_i u_i(r) \end{aligned} \]- free-atom like: $v_i(r) = v^\text{DFT}_\text{free atom}(r)$
- hydrogen-like: $v_i(r) = \frac{Z_i}{r}$
- free ions, harmonic oscillators (Gaussians), ...

↓

- List of NAO basis functions for all elements (1-102)
- From fast qualitative to meV-converged total energies (for LDA/GGA/hybrid density functionals)

How to construct them? All details in the paper

*V. Blum, R. Gehrke, F. Hanke, P. Havu,V. Havu, X. Ren, K. Reuter and M. Scheffler, “Ab Initio
Molecular Simulations with Numeric Atom-Centered Orbitals”, Computer Physics Communications 180,
2175-2196 (2009)*

Scalable Hybrid Density Functionals

- O(N) scaling implementation Levchenko
- Localized resolution of identity Ihrig
- Memory efficient: MPI-3 intra-node shared memory

of connected infrastructure

**GIMS**

Open, Free, Browser-Based Graphical Interface

Try it right now!

gims.ms1p.org

**Where to start**

A set of open introductory, open-access tutorials

Start with: Basics of Running FHI-aims