(input-file-variables-target)=
# Input file variables

```{attention}
Work in progress...
```

(yambo-input-variables-target)=
## Yambo input variables

A typical Yambo input file looks like this:

```{code-block} none
[...]
rim_cut              # [R] Coulomb potential
gw0                  # [R] GW approximation
el_el_corr           # [R] Electron-Electron Correlation
HF_and_locXC         # [R] Hartree-Fock
em1d                 # [R][X] Dynamically Screened Interaction
NLogCPUs=0           # [PARALLEL] Live-timing CPU`s (0 for all)
RandQpts=1000000     # [RIM] Number of random q-points in the BZ
CUTGeo= "slab z"     # [CUT] Coulomb Cutoff geometry: box/cylinder/sphere/ws/slab X/Y/Z/XY..
RandGvec= 5  Ry      # [RIM] Coulomb interaction RS components
NGsBlkXm= 1  Ry      # [Xm] Response block size
[...]
```

Note that each comment begins with a **marker**, 
for example `[R]`, `[RIM]`, `[CUT]` and so on. 
These markers identify different classes of variables 
that refer to specific sections of either the calculation or the code itself.
In the following, all the variables are grouped according 
to their reference marker(s). 

You may also notice that for some variables it is possible 
to specify the units: you will find the available options 
in the variable description.

---

```{card} 
[Runlevels](#runlevels-sec-target)
^^^

_Marker(s)_: `[R]`

These variables are used by the driver to determine what needs to be computed.
To each runlevel is connected a set of input variables.

[rim_cut](#var-rimcut-target), 
[gw0](#var-gw0-target)
```

```{card} 
[RIM and Coulomb cutoff](#rimandcutoff-sec-target)
^^^

_Marker(s)_: `[RIM]`, `[CUT]`

These variables control the random integration method and the cutoff 
geometry of the Coulomb interaction.

[RandQpts](#var-RandQpts-target), ...
```

---

(runlevels-sec-target)=
### Runlevels

Here all the variables related to the marker `[R]`.

```{line-block}
:name: var-rimcut-target

**`rim_cut`**
  Description
  ...
```
[> top](#yambo-input-variables-target)

```{line-block}
:name: var-gw0-target

**`gw0`**
  Description
  ...
```
[> top](#yambo-input-variables-target)

---

(rimandcutoff-sec-target)=
### RIM and Coulomb cutoff

Here all the variables related to the markers `[RIM]` and `[CUT]`.

```{line-block}
:name: var-RandQpts-target

**`RandQpts`**
  _Type_: INTEGER
  _Units_: RL
  _Default_: 100..?

  Number of random q-points in the BZ to perform Monte Carlo Integration. 
  Values like $10^6$ can be used to ensure convergence. 
  Needed for non 3D system to avoid divergences for small $q$, and needed to build cutoff potential with box shape.
```
```{versionadded} 4.0
Brief explanation...
```
[> top](#yambo-input-variables-target)