# Czechia 2026

This page provides the instructions and tutorials of Yambo hands-on sessions for the course organized by IT4I in collaboration with MaX CoE and NCC Czechia.

Webpage of the event: [Hands-on many-body calculations with the Yambo code](https://events.it4i.cz/event/393/).

```{card}
:margin: 5 5 auto auto
:width: 75%
:img-background: ../media/cz-it4i_handson_2026.png
:img-alt: it4i handson title
:link: https://events.it4i.cz/event/393/
```

---

## General instructions

### Scratch folder

The tutorial calculations should be run in the `/scratch` storage space. 
First, create a folder named with your username with the following command

```{code-block} none
$ mkdir /scratch/project/atr-25-5/YAMBO_SCHOOL/$USER
```

Then, add the following line in your `~/.bashrc` file:

```{code-block} none
export MY_SCRATCH=/scratch/project/atr-25-5/YAMBO_SCHOOL/${USER}
```
<!---
chmod -R 750 ${MY_SCRATCH}
-->

Finally, either type `source ~/.bashrc` in your terminal or log out and log back in. 
You should now be able to `cd` directly to your scratch folder:

```{code-block} none
$ cd $MY_SCRATCH
```

This is where you will copy the tutorial files and run the calculations.

### Gnuplot

During the tutorials it may be useful to quickly visualize some of the plots. 
You can use `gnuplot` from a **login** node. 
To do so, you must connect via `ssh -X` and load `gnuplot` with

```{code-block} none
$ module load gnuplot/5.4.6-GCCcore-12.2.0
```

```{note}
You can always copy the data to you local machine and plot them with your favourite tool.
```

---

## Tutorials

Follow the tutorials listed below (you may want to skip the optional sections present in some of them).

```{important}
Ignore the download instructions at the beginning of the tutorials. 
Instead, copy the tutorial files from 
`/scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/` 
in your scratch folder, as shown below.
```

### Getting started with Yambo

We will run this part on CPUs in interactive mode. 
First, open a CPU interactive session on a compute node with
```{code-block} none
$ salloc --account=ATR-25-5 --nodes=1 --ntasks-per-node=1 --cpus-per-task=1 --partition=qcpu_exp --time=01:00:00 --reservation=ATR-25-5_2026-05-05T09:00_2026-05-05T13:00__qcpu
```
then load Yambo with
```{code-block} none
$ source /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/load_yambo_cpu
```
(this also sets the `OMP_NUM_THREADS` environment variable).

1. **Optics at the independent particle level**
   ```{code-block} none
   $ cd $MY_SCRATCH
   $ cp -r /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/DAY_1/hBN .
   ```
   [Go to the tutorial](#optics-ipa-tutorial-target)

2. **RPA and local field effects**
   
   ```{code-block} none
   $ cd $MY_SCRATCH
   $ cp -r /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/DAY_1/hBN-2D .
   ```
   [Go to the tutorial](#local-fields-tutorial-target)

### Run Yambo on a HPC machine

We will run these tutorials on CPU and GPU, some parts in interactive mode and others via job submission scripts. 

1. **GW calculation and parallelization schemes**

   Open an interactive session on GPU with the following command
   ```{code-block} none
   $ salloc --account=ATR-25-5 --nodes=1 --ntasks-per-node=1 --gpus=1 --cpus-per-task=8 --partition=qgpu_exp --time=01:00:00 --reservation=ATR-25-5_2026-05-06T09:00_2026-05-06T13:00__qgpu
   ```
   Then load Yambo with
   ```{code-block} none
   $ source /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/load_yambo_gpu
   ```
   (this also sets the `OMP_NUM_THREADS` environment variable).
   ```{attention}
   When running in interactive mode on GPU, run Yambo with `mpirun yambo`.
   ```
   For this tutorial we also need `python`:
   ```{code-block} none
   $ source /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/load_python
   ```
   Now copy the files in your scratch directory:
   ```{code-block} none
   $ cd $MY_SCRATCH
   $ cp -r /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/DAY_2/MoS2_HPC_tutorial .
   ```
   [Go to the tutorial](#gw-on-mos2-hpc-tutorial-target)
   

2. **BSE calculation and solvers**

   Open an interactive session on CPU with the following command
   ```{code-block} none
   $ salloc --account=ATR-25-5 --nodes=1 --ntasks-per-node=1 --cpus-per-task=1 --partition=qcpu_exp --time=01:00:00 --reservation=atr-25-5_2026-05-07T09:00_2026-05-07T13:00__qcpu
   ```
   Then load Yambo with
   ```{code-block} none
   $ source /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/load_yambo_cpu
   ```
   (this also sets the `OMP_NUM_THREADS` environment variable).

   Now copy the files in your scratch directory:
   ```{code-block} none
   $ cd $MY_SCRATCH
   $ cp -r /scratch/project/atr-25-5/YAMBO_SCHOOL/TUTORIAL_FILES/DAY_3/MoS2_HPC_BSE_tutorial .
   ```
   [Go to the tutorial](#bse-on-mos2-hpc-tutorial-target)