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# Spin-orbit coupling in a Fe monolayer

## Contents

Spin-orbit coupling (SOC) in a freestanding Fe monolayer. This example is carried out in total analogy to Spin-orbit coupling in a Ni monolayer.

## Input

### POSCAR

```fcc Fe 100 surface
3.45
.50000   .50000   .00000
-.50000   .50000   .00000
.00000   .00000  5.00000
1
Cartesian
.00000   .00000   .00000
```

### INCAR

```SYSTEM        = Fe (100) monolayer
ISTART        = 0
ENCUT         = 270.00
LNONCOLLINEAR = .TRUE.
MAGMOM        = 0.0 0.0 3.0
VOSKOWN       = 1
LSORBIT       = .TRUE.

LMAXMIX       = 4
```
• For the second calculation, switch to in-plane magnetiztion by setting MAGMOM= 3.0 0.0 0.0.

### KPOINTS

```k-points
0
Monkhorst-Pack
9 9 1
0 0 0
```

## Calculation

• From the energy differences of the calculations using in plane and out of plane magnetization we see that the easy axis lies (in contrast to Ni) out of plane:

${\displaystyle E_{{{\textrm {MAE}}}}=E(m_{{\perp }})-E(m_{{\parallel }})=-0.2\,{\textrm {meV}}}$