# Parameters for calculating ZT

Parameters here are for calculating thermoelectric properties, including the thermoelectric figure of merit ZT and the related properties Seebeck coefficient S, electrical conductivity sigma, and thermal conductivity kappa with both lattice and electronic contributions.

## calculation.ZT.systemObjectFiles

**keyword**: calculation.ZT.systemObjectFiles

**possible values**: cells of file names

**default value**: no default value

**description**: It is supposed that the calculations for the electronic
Hamiltonian (SCF) and the phononic Hamiltonian (Hessian)
have already been completed seperatly. This parameter
gives in order the file names of the calculated
cNanodcal objects for the electronic and the phononic
calculations, or the calculated transmissions for
the electron and the phonon.

**an example**:

```
calculation.ZT.systemObjectFiles = ...
{'./electron/NanodcalObject.mat', ...
'./phonon/NanodcalObject.mat'}
```

## calculation.ZT.whatDirection

**keyword**: calculation.ZT.whatDirection

**possible values**: 1, 2, or 3

**default value**: 3

**description**: The transmission direction of the system, which need
to simulate. It is necessary to choose one and only
one of the three central cell vectors as the lead
direction (i.e. transmission direction); the transverse
plane is spanned by the other two directions.

**an example**:

```
calculation.ZT.whatDirection = 3
```

## calculation.ZT.temperature

**keyword**: calculation.ZT.temperature

**possible values**: n x 1 double array with n an integer

**default value**: 300

**description**: The electronic and phononic temperature of the system,
in the unit of K.

Note: the Boltzmann constant k = 8.617342e-05(eV/K) / 27.2113834(eV/Hartree) = 3.1668151e-06 (Hartree/K).

**an example**:

```
calculation.ZT.temperature = [50:50:500]
```

## calculation.ZT.chemicalPotentialEnergy

**keyword**: calculation.ZT.chemicalPotentialEnergy

**possible values**: n x 1 double array with proper energy unit such as
‘eV’, ‘meV’,
‘Ryd’, ‘Ryd.’, ‘Rydberg’,
‘au’, ‘a.u.’, ‘atomic unit’, ‘Hartree’,
where ‘au’ ‘a.u.’, and ‘atomic unit’ are for Hartree,
‘Ryd’, ‘Ryd.’ for Rydberg.

**default value**: 0

**description**: The thermoelectric figure of merit ZT and other related
properties will be calculated respectively when the
chemical potential energy is set to those input values.

Note that the chemical potential energy is measured from the calculated Fermi energy and is in the unit of meV.

**an example**:

```
calculation.ZT.chemicalPotentialEnergy = [0:10:100] meV
```

## calculation.ZT.kSpaceGridNumber

**keyword**: calculation.ZT.kSpaceGridNumber

**possible values**: 3 x 1 integer array

**default value**: the value of calculation.k_spacegrids.number which was
used in the electronic Hamiltonian calculation.

**description**: The number of small k-space grids in each direction,
which are used in the electronic k-space integration.

**an example**:

```
calculation.ZT.kSpaceGridNumber = [10 10 10]'
```

## calculation.ZT.qSpaceGridNumber

**keyword**: calculation.ZT.qSpaceGridNumber

**possible values**: 3 x 1 integer array

**default value**: the value of calculation.k_spacegrids.number which was
used in the original electronic Hamiltonian calculation.

**description**: The number of small q-space grids in each direction,
which are used in the phononic q-space integration.

**an example**:

```
calculation.ZT.qSpaceGridNumber = [10 10 10]'
```

## calculation.ZT.energyInterval

**keyword**: calculation.ZT.energyInterval

**possible values**: a double number with proper energy unit such as
‘eV’, ‘meV’,
‘Ryd’, ‘Ryd.’, ‘Rydberg’,
‘au’, ‘a.u.’, ‘atomic unit’, ‘Hartree’,
where ‘au’ ‘a.u.’, and ‘atomic unit’ are for Hartree,
‘Ryd’, ‘Ryd.’ for Rydberg.

**default value**: 0.3 (kT)

**description**: Energy interval used in the electronic and phononic
energy-space integration.

**an example**:

```
calculation.ZT.energyInterval = 2 meV
```

## calculation.ZT.plot

**keyword**: calculation.ZT.plot

**possible values**: true or false

**default value**: false

**description**: If true, a plot will be given after the calculation.

**an example**:

```
calculation.ZT.plot = true
```