# Parameters for calculating densityOfStates

Parameters here are for calculating the density of states (DOS).

## calculation.densityOfStates.method

keyword: calculation.densityOfStates.method

possible values: ‘GreenFunction’ or ‘WaveFunction’

default value: ‘WaveFunction’ for 1D, 2D, and 3D bulk systems, ‘GreenFunction’ for molecule and systems with probes.

description: The method used for the calculation of the density of states.

an example:

```calculation.densityOfStates.method = 'GreenFunction'
```

## calculation.densityOfStates.kSpaceGridNumber

keyword: calculation.densityOfStates.kSpaceGridNumber

possible values: 3 x 1 integer array

default value: the value of calculation.k_spacegrids.number which was used in the Hamiltonian calculation, or [1 1 1] if an user provided Hamiltonian is used.

description: number of small k-space grids in each direction which, together with kSpaceGridShift, are used to produce the parameter kSpacePoints.

an example:

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

## calculation.densityOfStates.kSpaceGridShift

keyword: calculation.densityOfStates.kSpaceGridShift

possible values: 3 x 1 or 1 x 3 array, [s_1, s_2, s_3], with each s_i a double number between 0 and 1.

default value: if the densityOfStates.kSpaceGridNumber is given, or if an user provided Hamiltonian is used, the default value is [0 0 0], otherwise the default value is the value of calculation.k_spacegrids.shift which was used in the hamiltonian calculation.

description: k-space grid point shift. While all s_i are set to be 0, the Gamma point is always among the k-space grid points being generated; otherwise, the k-space grid points will be shifted s_1, s_2, and s_3 grid length along their grid vector directions, respectively.

an example:

```calculation.densityOfStates.kSpaceGridShift = [1/2 1/2 1/2]'
```

## calculation.densityOfStates.energyRange

keyword: calculation.densityOfStates.energyRange

possible values: a 2 x 1 double array

default value: no default value

description: When isIntegrated is true, this parameter defines the energy range over which dos is integrated. When isIntegrated is false, this parameter is used together with numberOfEnergyPoints, to define the parameter energyPoints. Note that for bulk system its values are measured from the Fermi energy, and for system with leads its values are measured from the chemical potential of a lead that has zero applied voltage.

an example:

```calculation.densityOfStates.energyRange = [-10,10]
```

## calculation.densityOfStates.numberOfEnergyPoints

keyword: calculation.densityOfStates.numberOfEnergyPoints

possible values: an integer number

default value: 20 when isIntegrated is true and the method is ‘GreenFunction’, otherwise determined by parameters energyRange and energyInterval.

description: When isIntegrated is true, this parameter is used to perform the integration. When isIntegrated is false, this parameter is used together with energyRange, to define the parameter energyPoints.

an example:

```calculation.densityOfStates.numberOfEnergyPoints = 100
```

## calculation.densityOfStates.energyInterval

keyword: calculation.densityOfStates.energyInterval

possible values: a double number

default value: 5e-2 eV

description: Energy interval used to determine the parameter numberOfEnergyPoints.

an example:

```calculation.densityOfStates.energyInterval = 1e-3
```

## calculation.densityOfStates.energyPoints

keyword: calculation.densityOfStates.energyPoints

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

default value: Fermi energy or chemical potentials of all the leads when energyRange is not given; otherwise, determined by energyRange and numberOfEnergyPoints.

description: when isIntegrated is true, this parameter is used together with energyPointWeights, to perform the energy integration. When isIntegrated is false, the density of states will be calculated at those energy points. Note that for bulk system its values are measured from the Fermi energy, and for system with leads its values are measured from the chemical potential of a lead that has zero bias voltage.

an example:

```calculation.densityOfStates.energyPoints = 0
```

## calculation.densityOfStates.whatProjected

keyword: calculation.densityOfStates.whatProjected

possible values: ‘None’, ‘Atom’, ‘Orbital’, ‘Ell’

default value: ‘None’

description: If ‘Atom’ or ‘Orbital’, the dos is projected on the given orbitals or atoms. If ‘Ell’, the dos is projected on orbitals with the given angular momentum. If ‘None’, not projected.

an example:

```calculation.densityOfStates.whatProjected = 'Orbital'
```