Parameters for calculating phononDensityOfStates

Parameters here are for calculating the phonon density of states.


keyword: calculation.phononDensityOfStates.isResolved

possible values: true or false

default value: false

description: If true, the density of states (dos) is resolved in k-space, instead of integrated over the Brillouin zone.

an example:

calculation.phononDensityOfStates.isResolved = 0


keyword: calculation.phononDensityOfStates.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.phononDensityOfStates.kSpaceGridNumber = [10 10 10]'


keyword: calculation.phononDensityOfStates.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 phononDensityOfStates.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.phononDensityOfStates.kSpaceGridShift = [1/2 1/2 1/2]'


keyword: calculation.phononDensityOfStates.energyRange

possible values: a 2 x 1 double array with an unit of meV or THz or 1/cm.

default value: no default value

description: This parameter is used together with numberOfEnergyPoints, to define the parameter energyPoints.

an example:

calculation.phononDensityOfStates.energyRange = [0,30] meV


keyword: calculation.phononDensityOfStates.numberOfEnergyPoints

possible values: an integer number

default value: determined by parameters energyRange and energyInterval.

description: this parameter is used together with energyRange, to define the parameter energyPoints.

an example:

calculation.phononDensityOfStates.numberOfEnergyPoints = 100


keyword: calculation.phononDensityOfStates.energyInterval

possible values: a double number with an unit of meV or THz or 1/cm

default value: 0.5 meV

description: Energy interval used to determine the parameter numberOfEnergyPoints.

an example:

calculation.phononDensityOfStates.energyInterval = 1e-3


keyword: calculation.phononDensityOfStates.energyPoints

possible values: n x 1 double array with an unit of meV or THz or 1/cm, where the n is an integer

default value: determined by energyRange and numberOfEnergyPoints.

description: the density of states will be calculated at those energy points.

an example:

calculation.phononDensityOfStates.energyPoints = [0:30] meV


keyword: calculation.phononDensityOfStates.whatProjected

possible values: ‘None’, ‘Atom’, ‘Coordinate’

default value: ‘None’

description: If ‘Atom’ or ‘Coordinate’, the dos is projected on the given coordinates or atoms. If ‘None’, not projected.

an example:

calculation.phononDensityOfStates.whatProjected = 'Coordinate'


keyword: calculation.phononDensityOfStates.indexProjected

possible values: cell array of n x 1 integer array

default value: all atoms or coordinates

description: Each cell, which contains a n x 1 integer array to represent a set of atoms or coordinates, defines a projector. Density of states projected on each set of those atoms or coordinates will be calculated respectively. This parameter is not used when whatProjected is ‘None’.

an example:

calculation.phononDensityOfStates.indexProjected = ...
{[1 4 7], [2 5 8], [3 6 9]}


keyword: calculation.phononDensityOfStates.eta

possible values: a small double number

default value: 5e-2 eV

description: The Lorentz broadening width used to smooth the dos when the GreenFunction method is used. Note that the unit used is defined by input parameter calculation.control.energyUnit, and default unit is eV.

an example:

calculation.phononDensityOfStates.eta = 1e-2


keyword: calculation.phononDensityOfStates.plot

possible values: true or false

default value: false

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

an example:

calculation.phononDensityOfStates.plot = true


keyword: calculation.phononDensityOfStates.broadening

possible values: 0, 1, 2

default value: 0

description: The calculated density of states as a function of energy may not look smooth enough and it normally needs to do the gaussian broadening to make it looks more smooth. If it is 0, do not do the broadening. If it is 1, do the broadening by using a gaussian function as the broadening function, where the standard deviation parameter of the gaussian function is defined through the input parameter broadeningWidth. If it is 2, re-do the broadening (with a different broadening width) on the density of states which has already been calculated before.

an example:

calculation.phononDensityOfStates.broadening = 2


keyword: calculation.phononDensityOfStates.broadeningWidth

possible values: a small double number

default value: 2

description: The half width at half maximum (HWHM) of the broadening function, in the unit of the minimum interval between the energy points. For a gaussian function with a standard deviation SD, the HWHM is sqrt(2ln2)*SD,

an example:

calculation.phononDensityOfStates.broadeningWidth = 4