### Fortran Namelist Example

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/input.md

Illustrates the basic syntax for Fortran 90 namelists, showing how to set variables and use comments.

```default
&NAMELIST
needed_variable2=XX, needed_variable1=YY,
character_variable1='a suitable string'
/

```

--------------------------------

### Minimal wt.in Structure Example

Source: https://context7.com/quanshengwu/wannier_tools/llms.txt

A minimal wt.in file structure demonstrating NAMELISTS and INPUT_CARDs. All parameters have defaults; only set what you need.

```fortran
! ── TB_FILE namelist ──────────────────────────────────────────────────────────
&TB_FILE
Hrfile  = 'wannier90_hr.dat'   ! tight-binding Hamiltonian file
Package = 'VASP'               ! 'VASP', 'QE', 'Wien2k', 'OpenMx', 'Abinit'
/

! ── CONTROL namelist: activate calculations ───────────────────────────────────
&CONTROL
BulkBand_calc        = T
SlabSS_calc          = T
Z2_3D_calc           = T
/

! ── SYSTEM namelist ───────────────────────────────────────────────────────────
&SYSTEM
NumOccupied = 18      ! Number of occupied Wannier bands (not electrons)
SOC         = 1       ! 0 = no SOC, 1 = SOC included in hr.dat
E_FERMI     = 4.4195  ! Fermi energy in eV (from first-principles output)
NSLAB       = 10      ! Slab thickness for surface calculations
/

! ── PARAMETERS namelist ───────────────────────────────────────────────────────
&PARAMETERS
Nk1        = 101      ! k-points along 1st direction
Nk2        = 101      ! k-points along 2nd direction
Nk3        = 21       ! k-points along 3rd direction
OmegaMin   = -0.6     ! Energy window minimum (eV)
OmegaMax   =  0.5     ! Energy window maximum (eV)
OmegaNum   = 401      ! Energy slices in [OmegaMin, OmegaMax]
Eta_Arc    = 0.001    ! Broadening η for Green's function (eV)
E_arc      = 0.0      ! Fixed energy for Fermi arc / QPI (eV)
NP         = 2        ! Number of principal layers (iterative GF)
Gap_threshold = 1.0   ! Print k-points with gap < this value
/

! ── LATTICE card ──────────────────────────────────────────────────────────────
LATTICE
Angstrom
-2.069  -3.583614  0.000000
 2.069  -3.583614  0.000000
 0.000   2.389075  9.546667

! ── ATOM_POSITIONS card ───────────────────────────────────────────────────────
ATOM_POSITIONS
5               ! number of atoms with projectors
Direct
 Bi 0.3990  0.3990  0.6970
 Bi 0.6010  0.6010  0.3030
 Se 0.0000  0.0000  0.5000
 Se 0.2060  0.2060  0.1180
 Se 0.7940  0.7940  0.8820

! ── PROJECTORS card ───────────────────────────────────────────────────────────
PROJECTORS
 3 3 3 3 3      ! projectors per atom (orbital only, no spin)
 Bi pz px py
 Bi pz px py
 Se pz px py
 Se pz px py
 Se pz px py

! ── SURFACE card ──────────────────────────────────────────────────────────────
SURFACE            ! two lattice vectors spanning the surface
 1  0  0
 0  1  0

! ── k-path cards ──────────────────────────────────────────────────────────────
KPATH_BULK
4
G 0.00000 0.00000 0.0000  Z 0.00000 0.00000 0.5000
Z 0.00000 0.00000 0.5000  F 0.50000 0.50000 0.0000
F 0.50000 0.50000 0.0000  G 0.00000 0.00000 0.0000
G 0.00000 0.00000 0.0000  L 0.50000 0.00000 0.0000

KPATH_SLAB
2
K  0.33  0.67  G  0.0  0.0
G  0.0   0.0   M  0.5  0.5

KPLANE_SLAB
-0.1 -0.1
 0.2  0.0
 0.0  0.2

KPLANE_BULK
 0.00  0.00  0.00
 1.00  0.00  0.00
 0.00  0.50  0.00

KCUBE_BULK
-0.50 -0.50 -0.50
 1.00  0.00  0.00
 0.00  1.00  0.00
 0.00  0.00  1.00
```

--------------------------------

### Bi2Se3 Bulk Band Calculation Example

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Steps to perform a bulk band calculation for Bi2Se3, including copying input files and running the executable.

```shell
$ cd examples/Bi2Se3
$ cp wt.in-bands wt.in
$ ../../bin/wt.x
$ gnuplot bulkek.gnu
```

--------------------------------

### Graphene Bulk Band Calculation Example

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Steps to perform a bulk band calculation for Graphene, including copying input files and running the executable.

```shell
$ cd examples/Graphene
$ cp wt.in-bands wt.in
$ ../../bin/wt.x
$ gnuplot bulkek.gnu
```

--------------------------------

### Setup Input Files for Wilson Loop Calculation

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/TBG-2.44degree/readme.txt

Copies the base input file and extracts the Hamiltonian data required for the Wilson loop and flat band calculations.

```bash
cp wt.in-wilsonloop-flatbands wt.in
```

```bash
tar xzvf TBG_hr.dat.tar.gz
```

--------------------------------

### Dense Format TB Parameters Example

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/input.md

This example shows the typical structure of a dense format file containing TB parameters. It includes a comment line, the number of Wannier orbitals, the number of R lattice vectors, and the TB parameters themselves.

```default
written on  8May2016 at 13:57:00
         30
        547
   2    2    1    1    1    1    1    1    1    1    2    2    2    2    2
   1    1    1    2    1    1    1    2    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   2    2    2    2    2    2    2    4    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    2    1
   1    1    1    1    1    1    2    1    1    1    1    1    1    1    1
   2    2    2    2    2    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    2    1    1    1    1
   1    1    1    2    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    2    2    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    2    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    2    1    1    1    2    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    2
   1    1    1    1    1    1    1    2    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    2    1    1    1    2    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    2    1    1    1    1    1    1    1    2    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    2    2    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    2    1    1    1    1    1    1    1    2    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    2    2    2    2    2    1    1    1    1    1    1    1    1
   2    1    1    1    1    1    1    1    2    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    4
   2    2    2    2    2    2    2    4    1    1    1    1    1    1    1
   1    1    1    1    1    1    1    1    1    1    1    1    1    1    2
   1    1    1    2    1    1    1    2    2    2    2    2    1    1    1
   1    1    1    1    1    2    2
  -6    2   -3    1    1   -0.000002    0.000003
  -6    2   -3    2    1    0.000002    0.000017
  -6    2   -3    3    1   -0.000053    0.000002
  -6    2   -3    4    1   -0.000031    0.000002
  -6    2   -3    5    1    0.000001   -0.000000
  -6    2   -3    6    1   -0.000003    0.000002
  -6    2   -3    7    1    0.000037   -0.000001
  -6    2   -3    8    1   -0.000001   -0.000003
  -6    2   -3    9    1   -0.000005   -0.000003
  -6    2   -3   10    1   -0.000062   -0.000001
  -6    2   -3   11    1   -0.000001    0.000001
  -6    2   -3   12    1   -0.000031    0.000002
  -6    2   -3   13    1    0.000011   -0.000000
  -6    2   -3   14    1   -0.000001    0.000001
  -6    2   -3   15    1    0.000003    0.000003
  -6    2   -3   16    1    0.000000   -0.000010
  -6    2   -3   17    1   -0.000010   -0.000001
  -6    2   -3   18    1   -0.000000   -0.000008
  -6    2   -3   19    1    0.000000    0.000000
  -6    2   -3   20    1    0.000012   -0.000002
  ......
```

--------------------------------

### Run Bulk Spin Texture Calculation

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Steps to run a bulk spin texture calculation. Ensure you are in the example directory and have copied the input file.

```bash
$ cd examples/TiB2/
$ cp wt.in-fs_kplane wt.in
$ mpiexec -np 8 ../../bin/wt.x
$ gnuplot fs_kplane.gnu
```

--------------------------------

### Bi2Se3 Strong Topological Insulator Workflow

Source: https://context7.com/quanshengwu/wannier_tools/llms.txt

End-to-end workflow for Bi2Se3, calculating bulk band structure, Z2 index, and surface states. This example demonstrates the typical steps for analyzing topological insulators.

```bash
cd examples/Bi2Se3

# ── Step 1: Bulk band structure ───────────────────────────────────────────────
cp wt.in-bands wt.in
../../bin/wt.x
gnuplot bulkek.gnu      # → bulkek.eps

# ── Step 2: Z2 topological index ─────────────────────────────────────────────
cp wt.in-z2 wt.in       # sets Z2_3D_calc = T, NumOccupied=18, Nk1=Nk2=41
../../bin/wt.x
gnuplot wanniercenter3D_Z2.gnu   # → 6 WCC panels
grep "z2 number" WT.out
# Expected output:  z2 number for 6 planes:  1  0  1  0  1  0
# → Z2 index (v0;v1v2v3) = (1;000) → strong topological insulator

# ── Step 3: Surface states (ARPES) + Fermi arcs ───────────────────────────────
cp wt.in-surfacestates wt.in   # sets SlabSS_calc=T, SlabArc_calc=T
mpirun -np 4 ../../bin/wt.x
gnuplot surfdos_l.gnu   # → surface ARPES spectrum (top surface, (0001))
gnuplot arc_l.gnu       # → Fermi arc at E=0 (Dirac surface cone

```

--------------------------------

### CONTROL Namelist for Task Setup

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/input.md

Enables or disables various calculation tasks. Multiple tasks can be set to true simultaneously to perform combined analyses.

```default
&CONTROL
BulkBand_calc         = T        ! bulk band structure calculation flag
BulkFS_calc           = F
BulkGap_cube_calc     = F
BulkGap_plane_calc    = F
SlabBand_calc         = T
WireBand_calc         = F
SlabSS_calc           = T
SlabArc_calc          = F
SlabSpintexture_calc  = T
wanniercenter_calc    = F
BerryCurvature_calc   = F
/

```

--------------------------------

### Configure 3D Fermi Surface Calculation

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Input namelist and k-point grid configuration for a 3D Fermi surface calculation. Ensure KCUBE_BULK starts at (0,0,0) for standard visualization.

```fortran
&CONTROL
BulkFS_calc = T
/
&PARAMETERS
Nk1 = 101   ! No. of slices for the 1st reciprocal vector
Nk2 = 101   ! No. of slices for the 2nd reciprocal vector
Nk3 = 101   ! No. of slices for the 3rd reciprocal vector
/

KCUBE_BULK
  0.00  0.00  0.00   ! Original point for 3D k plane, For BulkFS_calc, this should be always be 0 0 0
  1.00  0.00  0.00   ! The first vector to define 3d k space plane
  0.00  1.00  0.00   ! The second vector to define 3d k space plane
  0.00  0.00  1.00   ! The third vector to define 3d k cube
```

--------------------------------

### Prepare System Input File

Source: https://github.com/quanshengwu/wannier_tools/blob/master/utility/twisted_graphene_system_tight_binding/readme.md

Configure the system parameters by creating a 'system.in' file. This file specifies details like the number of layers, twist angle, stacking sequences, and parameters for generating the tight-binding Hamiltonian.

```fortran
! an example for Twisted A-AB system
&PARAMETERS
number_layers = 3    ! number of layers 
twisted_index_m= 1   ! twisted index m, the twist angle theta= acos((3d0*m*m + 3d0*m + 0.5d0)/(3d0*m*m + 3d0*m + 1d0));
twisted_angle_array_input = 0 1 1  ! twisted angle array, unit is theta; Number_of_layers numbers
stacking_sequences_input = "A" "A"  "B" ! AB stacking sequences, only three values "A", "B", "C"; Number_of_layers numbers
use_poscar = F    ! use POSCAR or not, "=F" we will generate POSCAR, "=T" we will use the provided POSCAR to generate hr.dat.
hr_generate = T    ! Generate hr.dat or not,  "=T" we will generate hr.dat
gen_sparse_hr = T   ! Choose sparse or dense stored hr.dat,  "=T" we will generate hr.dat in sparse format
hr_cutoff=0.00010  ! set HmnR=0 if HmnR<hr_cutoff in unit of eV
vpppi=-2.81       ! pi bond of p orbital, in unit of eV
iR_cut = 1   ! R is in [-iR_cut, -iR_cut+1, ..., iR_cut]
/

```

--------------------------------

### Get Band Structure of C-Vacancy Diamond

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/band_unfolding/C_vacancy_Diamond/README.txt

Commands to extract, configure, run, and visualize the band structure of C-vacancy Diamond.

```bash
tar xzvf C_vacancy_Diamond_hr.dat.tar.gz
cp wt.in-bands_C_vacancy_Diamond wt.in
wt.x
gnuplot bulkek.gnu
cp bulkek.pdf C_vacancy_Diamond-bulkek.pdf
```

--------------------------------

### Get Band Structure of Pure Diamond

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/band_unfolding/C_vacancy_Diamond/README.txt

Commands to extract, configure, run, and visualize the band structure of pure Diamond.

```bash
tar xzvf Diamond_hr.dat.tar.gz
cp wt.in-Diamond wt.in
wt.x
gnuplot bulkek.gnu
cp bulkek.pdf Diamond-bulkek.pdf
```

--------------------------------

### Get Band Structure of Si-doped Diamond

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/band_unfolding/Si_dopped_Diamond/README.txt

Commands to extract, copy configuration, run, and plot the band structure of Si-doped Diamond.

```bash
tar xzvf Si_dopped_Diamond_hr.dat.tar.gz
cp wt.in-bands_Si_dopped_Diamond wt.in
wt.x
gnuplot bulkek.gnu
cp bulkek.pdf Si_dopped_Diamond-bulkek.pdf
```

--------------------------------

### Build and Run WannierTools

Source: https://context7.com/quanshengwu/wannier_tools/llms.txt

Instructions for cloning the repository, compiling the Fortran code with MPI, and setting up the environment to run serial or parallel calculations.

```bash
# Clone the repository
git clone https://github.com/quanshengwu/wannier_tools.git
cd wannier_tools/src

# Edit Makefile to point libs= to your LAPACK+BLAS (e.g., Intel MKL)
# Choose one of: Makefile.gfortran, Makefile.intel, Makefile.intel-mpi
cp Makefile.intel-mpi Makefile
# Edit: FC = mpiifort, libs = -L$(MKLROOT)/lib/intel64 -lmkl_...

make         # binary is copied to ../bin/wt.x

# Add to PATH
export PATH=/path/to/wannier_tools/bin:$PATH

# Required input files in the working directory:
#   1. wt.in             – control and parameter file
#   2. wannier90_hr.dat  – tight-binding Hamiltonian from Wannier90

# Serial run
wt.x &

# MPI parallel run (recommended for large k-meshes)
mpirun -np 8 wt.x &

# Output: WT.out (log), plus calculation-specific .dat and .gnu files
```

--------------------------------

### Run Band Calculation with WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/TBG-13.2degree/readme.txt

Sets up and runs a band structure calculation. Copy the band input file to wt.in and execute the WannierTools binary.

```bash
cp wt.in-band wt.in
wt.x &
```

--------------------------------

### Quick Phonon Calculation with WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/FeSi/README.txt

This snippet shows the basic steps for a quick phonon calculation. It involves extracting a data file and running the WannierTools executable with MPI.

```bash
tar -xzvf phonopyTB_hr.dat.tar.gz
mpiexec -np 4 wt.x &
```

--------------------------------

### Get Bulk Fermi Surface in Fixed k Plane

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Cu/Readme.txt

Retrieves the bulk Fermi surface within a specific k-plane. Requires `wt.in-FS-contour` and `wannier90_hr.dat_nsymm48`.

```bash
mkdir FS-contour
cp wannier90_hr.dat_nsymm48 FS-contour/
cp wt.in-FS-contour FS-contour/wt.in
cd FS-contour
mpirun -np 4 wt.x &
gnuplot fs_kplane.gnu
```

--------------------------------

### Prepare Input Files for Phonon Calculation

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/FeSi/README.txt

This section details the necessary input files for generating a Tight-Binding (TB) model for phonon calculations. It includes POSCAR for atomic positions, FORCE_CONSTANTS for force data, and band.conf for configuration.

```text
ATOM_NAME = Fe Si
DIM = 3 3 3
FORCE_CONSTANTS = READ
BAND = 0.5 0 0 0 0 0 0.5  0.5  0.5  0.5  0.5 0 
BAND_POINTS=100
FC_SYMMETRY = 1
fc_spg_symmetry = .true.
```

--------------------------------

### Generate Trivial Insulator Model and Run WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Haldane_model/README.txt

Generates the tight-binding model for the trivial insulator phase, copies the input file, and runs WannierTools. Ensure you have the necessary Python scripts and WannierTools executable.

```bash
python haldane_hr_gen-trivial-insulator.py
cp wt.in-trivial-insulator  wt.in
mpirun -np 2 wt.x &
```

--------------------------------

### Modify Gnuplot Script for Band Plotting

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Example modification for the gnuplot script to correctly plot a specific number of bands, shown for Graphene with 2 total bands.

```gnuplot
splot ‘bulkek_plane.dat’ u 4:5:**7** w pm3d, ‘bulkek_plane.dat’ u 4:5:**8** w pm3d
```

--------------------------------

### Run Band Unfolding Calculation with WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/TBG-13.2degree/readme.txt

Sets up and runs a band unfolding calculation. Copy the band unfolding input file to wt.in and execute the WannierTools binary.

```bash
cp wt.in-bandunfold wt.in
wt.x &
```

--------------------------------

### Get Momentum k Evolution under Magnetic Field

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Cu/Readme.txt

Observes the evolution of momentum k under a magnetic field. Check the `evolve_band_6.dat` file for k-point evolution. Requires `wt.in-OHE-evolve` and `wannier90_hr.dat_nsymm48`.

```bash
mkdir OHE-evolve
cp wannier90_hr.dat_nsymm48 OHE-evolve/
cp wt.in-OHE-evolve OHE-evolve/wt.in
cd OHE-evolve
mpirun -np 4 wt.x 
```

--------------------------------

### Run WannierTools (Single Core)

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/installation.md

Execute the WannierTools program using the 'wt.x' command. The '&' symbol runs the process in the background.

```default
wt.x &
```

--------------------------------

### Define 3D k-plane for WCC Calculation (k1=0.5)

Source: https://github.com/quanshengwu/wannier_tools/wiki/Bi2Se3

Defines the original point and two vectors to specify a 3D k-plane for Wannier charge center calculations. This example sets k1=0.5.

```fortran
KPLANE_BULK
0.50 0.00 0.00   ! Original point for 3D k plane
0.00 1.00 0.00 ! The first vector to define 3d k space plane
0.00 0.00 0.50 ! The second vector to define 3d k space plane
```

--------------------------------

### Run Wannier Tools for Spin Hall Conductivity

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Pt/readme.txt

Extract the necessary data and run the `wt.x` executable to calculate spin Hall conductivity. Ensure you have 8 cores available for optimal performance.

```bash
tar xzvf wannier90_hr.dat.tar.gz
mpiexec -np 8 wt.x &
```

--------------------------------

### Define 3D k-plane for WCC Calculation (k2=0.5)

Source: https://github.com/quanshengwu/wannier_tools/wiki/Bi2Se3

Defines the original point and two vectors to specify a 3D k-plane for Wannier charge center calculations. This example sets k2=0.5.

```fortran
KPLANE_BULK
0.00 0.50 0.00   ! Original point for 3D k plane
1.00 0.00 0.00 ! The first vector to define 3d k space plane
0.00 0.00 0.50 ! The second vector to define 3d k space plane
```

--------------------------------

### Define 3D k-plane for WCC Calculation (k2=0.0)

Source: https://github.com/quanshengwu/wannier_tools/wiki/Bi2Se3

Defines the original point and two vectors to specify a 3D k-plane for Wannier charge center calculations. This example sets k2=0.0.

```fortran
KPLANE_BULK
0.00 0.00 0.00   ! Original point for 3D k plane
1.00 0.00 0.00 ! The first vector to define 3d k space plane
0.00 0.00 0.50 ! The second vector to define 3d k space plane
```

--------------------------------

### Generate Gapless Semimetal Model and Run WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Haldane_model/README.txt

Generates the tight-binding model for the gapless semimetal phase, copies the input file, and runs WannierTools. Ensure you have the necessary Python scripts and WannierTools executable.

```bash
python haldane_hr_gen-gapless.py
cp wt.in-gapless wt.in
mpirun -np 2 wt.x &
```

--------------------------------

### Bulk Band Calculation Input

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Configure bulk band calculations using the wt.in file. Specify k-point paths and orbitals for projection.

```default
&CONTROL
BulkBand_calc = T
/
&PARAMETERS
Nk1 = 101   ! Number of k points for each k line
/

! get projected bands onto different orbitals, here we only consider orbital and omit the spin freedom
SELECTED_WANNIERORBITALS
2
1-6                ! Bi
7-15               ! Se

KPATH_BULK     ! k point path
4              ! number of k lines only for bulk band
G 0.00000 0.00000 0.0000 Z 0.00000 0.00000 0.5000
Z 0.00000 0.00000 0.5000 F 0.50000 0.50000 0.0000
F 0.50000 0.50000 0.0000 G 0.00000 0.00000 0.0000
G 0.00000 0.00000 0.0000 L 0.50000 0.00000 0.0000

```

--------------------------------

### Define 3D k-plane for WCC Calculation (k3=0.5)

Source: https://github.com/quanshengwu/wannier_tools/wiki/Bi2Se3

Defines the original point and two vectors to specify a 3D k-plane for Wannier charge center calculations. This example sets k3=0.5.

```fortran
KPLANE_BULK
0.00 0.00 0.50   ! Original point for 3D k plane
1.00 0.00 0.00 ! The first vector to define 3d k space plane
0.00 0.50 0.00 ! The second vector to define 3d k space plane
```

--------------------------------

### Define 3D k-plane for WCC Calculation (k3=0.0)

Source: https://github.com/quanshengwu/wannier_tools/wiki/Bi2Se3

Defines the original point and two vectors to specify a 3D k-plane for Wannier charge center calculations. This example sets k3=0.0.

```fortran
KPLANE_BULK
0.00 0.00 0.00   ! Original point for 3D k plane
0.00 1.00 0.00 ! The first vector to define 3d k space plane
0.00 0.00 0.50 ! The second vector to define 3d k space plane
```

--------------------------------

### Generate Chern Insulator Model and Run WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Haldane_model/README.txt

This section follows the same steps as the trivial insulator phase but uses `haldane_hr_gen-chern-insulator.py` and `wt.in-chern-insulator` for the Chern insulator phase.

```bash
# The specific commands are analogous to the trivial insulator phase, replacing the filenames.
```

--------------------------------

### Configure Bulk Spin Texture Calculation

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Configure the `wt.in` file for bulk spin texture calculations. Specify parameters like NSLAB, E_FERMI, and k-point sampling.

```default
&CONTROL
BulkSpintexture_calc   =  T
/

&SYSTEM
NSLAB    =   1          ! for thin film system
NumOccupied = 144       ! NumOccupied
E_FERMI  =   2.5519
SOC      =   1
/

&PARAMETERS
Nk1      =   21      ! number k points  odd number would be better
Nk2      =   21      ! number k points  odd number would be better
E_arc    =   0.3     ! iso-energy
eta_arc  =   0.001   ! infinite small value, like broadening
/

SELECTED_ATOMS    ! projection only onto the selected atoms
2 ! number groups of selected atoms
6 12 18 24 30  ! top surface's atoms
1  7 13 19 25  ! bottom surface's atoms
```

--------------------------------

### Calculate Magnetoresistance (MR)

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Cu/Readme.txt

Calculates MR for different magnetic fields along specified angles. This involves repeating the setup for each angle. Ensure `wt.in-OHE-thetaX` and `wannier90_hr.dat_nsymm48` are correctly named and placed.

```bash
mkdir OHE-theta0
cp wannier90_hr.dat_nsymm48 OHE-theta0/
cp wt.in-OHE-theta0 OHE-theta0/wt.in
cd OHE-theta0
mpirun -np 4 wt.x &
cp rho_total_mu_0.00eV.dat ../rho_total_mu_0.00eV.dat-theta0
cd ..

mkdir OHE-theta45
cp wannier90_hr.dat_nsymm48 OHE-theta45/
cp wt.in-OHE-theta0 OHE-theta45/wt.in
cd OHE-theta45
mpirun -np 4 wt.x &
cp rho_total_mu_0.00eV.dat ../rho_total_mu_0.00eV.dat-theta45
cd ..
gnuplot rhotheta.gnu
```

--------------------------------

### Define Selected Atoms for Surface Spin Texture

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/Bi2Se3-6Qlayers/Readme.txt

Specify the groups of atoms to be included in the spin texture calculation. The indices correspond to those in ATOM_POSITIONS. This example selects atoms for both the top and bottom surfaces.

```plaintext
SELECTED_ATOMS
2 ! number groups of selected atoms
6 12 18 24 30  ! top surface's atoms
1  7 13 19 25  ! bottom surface's atoms
```

--------------------------------

### Add WannierTools to System PATH

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/installation.md

Append this command to your .bashrc file to make the 'wann_tools' binary accessible from any directory. Replace '/where/you/downloaded/wannier_tools' with the actual path to your downloaded WannierTools directory.

```default
export PATH=/where/you/downloaded/wannier_tools/bin:$PATH
```

--------------------------------

### Get Band Structure of Twisted Bilayer Graphene

Source: https://github.com/quanshengwu/wannier_tools/blob/master/examples/band_unfolding/twisted_bilayer_graphene_13.2degree/README.txt

Calculates and visualizes the band structure for twisted bilayer graphene. This involves copying the input file, running the WannierTools executable, and plotting the results.

```bash
cp wt.in-bands wt.in
mpirun -np 2 wt.x 
gnuplot bulkek.gnu
evince bulkek.pdf
```

--------------------------------

### Full WannierTools Configuration for Bi2Se3

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/tutorials/Bi2Se3.html

This snippet shows a comprehensive configuration for Bi2Se3 calculations, including settings for bulk bands, slab properties, spin texture, and topological invariants. It specifies lattice parameters, atomic positions, projectors, and k-point paths for bulk and slab calculations.

```fortran
&TB_FILE
Hrfile = 'wannier90_hr.dat'
/


&CONTROL
BulkBand_calc         = T
BulkFS_calc           = F
BulkGap_cube_calc     = F
BulkGap_plane_calc    = F
SlabBand_calc         = T
WireBand_calc         = F
SlabSS_calc           = T
SlabArc_calc          = T
SlabQPI_calc          = F
Z2_3D_calc            = T
Chern_3D_calc         = F
SlabSpintexture_calc  = F
Wanniercenter_calc    = F
BerryPhase_calc       = F
BerryCurvature_calc   = F
EffectiveMass_calc    = F
/

&SYSTEM
NSLAB = 10              ! for thin film system
NSLAB1= 4               ! nanowire system
NSLAB2= 4               ! nanowire system
NumOccupied = 18        ! NumOccupied
SOC = 1                 ! soc
E_FERMI = 4.4195        ! e-fermi
Bx= 0, By= 0, Bz= 0     ! Bx By Bz
surf_onsite= 0.0        ! surf_onsite
/

&PARAMETERS
Eta_Arc = 0.001     ! infinite small value, like brodening
E_arc = 0.0         ! energy for calculate Fermi Arc
OmegaNum = 401      ! omega number
OmegaMin = -0.6     ! energy interval
OmegaMax =  0.5     ! energy interval
k1 = 41            ! number k points  odd number would be better
k2 = 41           ! number k points  odd number would be better
k3 = 21           ! number k points  odd number would be better
NP = 1              ! number of principle layers
Gap_threshold = 1.0 ! threshold for GapCube output
/

LATTICE
Angstrom
-2.069  -3.583614  0.000000     ! crystal lattice information
 2.069  -3.583614  0.000000
 0.000   2.389075  9.546667

ATOM_POSITIONS
5                               ! number of atoms for projectors
Direct                          ! Direct or Cartisen coordinate
 Bi 0.3990    0.3990    0.6970
 Bi 0.6010    0.6010    0.3030
 Se 0     0     0.5
 Se 0.2060    0.2060    0.1180
 Se 0.7940    0.7940    0.8820

PROJECTORS
 3 3 3 3 3          ! number of projectors
Bi px py pz         ! projectors
Bi px py pz
Se px py pz
Se px py pz
Se px py pz

SURFACE            ! See doc for details
 1  0  0
 0  1  0
 0  0  1

KPATH_BULK            ! k point path
4              ! number of k line only for bulk band
G 0.00000 0.00000 0.0000 Z 0.00000 0.00000 0.5000
Z 0.00000 0.00000 0.5000 F 0.50000 0.50000 0.0000
F 0.50000 0.50000 0.0000 G 0.00000 0.00000 0.0000
G 0.00000 0.00000 0.0000 L 0.50000 0.00000 0.0000

KPATH_SLAB
2        ! numker of k line for 2D case
K 0.33 0.67 G 0.0 0.0  ! k path for 2D case
G 0.0 0.0 M 0.5 0.5

KPLANE_SLAB
-0.1 -0.1      ! Original point for 2D k plane
 0.2  0.0      ! The first vector to define 2D k plane
 0.0  0.2      ! The second vector to define 2D k plane  for arc plots

KPLANE_BULK
 0.00  0.00  0.50   ! Original point for 3D k plane  k3=0.5, bar{a}, along k1
 1.00  0.00  0.00   ! The first vector to define 3d k space plane
 0.00  0.50  0.00   ! The second vector to define 3d k space plane

!> The following 5 matrices are for backup using, will not affect the main input for WannierTools
 0.00  0.00  0.00   ! Original point for 3D k plane  k3=0.0, bar{a}, along k1
 1.00  0.00  0.00   ! The first vector to define 3d k space plane
 0.00  0.50  0.00   ! The second vector to define 3d k space plane

```

--------------------------------

### KPATH_SLAB for Slab Material k-point Path

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/input.md

Defines the high-symmetry k-point path for 2D slab calculations. Specify the number of k-lines and then the start and end points for each line using fractional coordinates.

```default
KPATH_SLAB
2        ! numker of k line for 2D case
K 0.33 0.67 G 0.0 0.0  ! k path for 2D case
G 0.0 0.0 M 0.5 0.5

```

--------------------------------

### Phonon System Configuration

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/input.md

Configure WannierTools to use phonon data. Specify the tight-binding Hamiltonian file and set the particle type to 'phonon'.

```fortran
&TB_FILE
Hrfile = 'phonopyTB_hr.dat'
Particle = 'phonon'
/

```

--------------------------------

### Bulk Band Calculation (Points Mode) Input

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/features.md

Configure WannierTools for bulk band structure calculations using discrete k-points. Ensure the KPOINTS_3D card is correctly formatted with the number of k-points and their coordinates.

```default
&CONTROL
BulkBand_points_calc = T
/

KPOINTS_3D
4              ! number of k points
Direct         ! Direct or Cartesian
0.00000 0.00000 0.0000
0.00000 0.00000 0.5000
0.50000 0.50000 0.0000
0.00000 0.00000 0.0000

```

--------------------------------

### Calculate Bulk Band Structure with WannierTools

Source: https://github.com/quanshengwu/wannier_tools/blob/master/doc/source/tutorials/Bi2Se3.html

Configure WannierTools to calculate the bulk band structure. Ensure SOC is enabled and set the Fermi energy. An odd number of k-points is recommended for Nk1.

```in
&CONTROL
BulkBand_calc         = T
/

&SYSTEM
SOC = 1                 ! soc
E_FERMI = 4.4195        ! e-fermi
/

&PARAMETERS
Nk1 = 41            ! number k points  odd number would be better
/

KPATH_BULK            ! k point path
4              ! number of k line only for bulk band
G 0.00000 0.00000 0.0000 Z 0.00000 0.00000 0.5000
Z 0.00000 0.00000 0.5000 F 0.50000 0.50000 0.0000
F 0.50000 0.50000 0.0000 G 0.00000 0.00000 0.0000
G 0.00000 0.00000 0.0000 L 0.50000 0.00000 0.0000
```