pymatgen.phonon.dos module¶

class
CompletePhononDos
(structure, total_dos, pdoss)[source]¶ Bases:
pymatgen.phonon.dos.PhononDos
This wrapper class defines a total dos, and also provides a list of PDos.
 Parameters
structure – Structure associated with this particular DOS.
total_dos – total Dos for structure
pdoss – The pdoss are supplied as an {Site: Densities}

pdos
¶ Dict of partial densities of the form {Site:Densities}

class
PhononDos
(frequencies, densities)[source]¶ Bases:
monty.json.MSONable
Basic DOS object. All other DOS objects are extended versions of this object.
 Parameters
frequencies – A sequences of frequencies in THz
densities – A list representing the density of states.

cv
(t, structure=None)[source]¶ Constant volume specific heat C_v at temperature T obtained from the integration of the DOS. Only positive frequencies will be used. Result in J/(K*molc). A molc is the abbreviation of a molecell, that is, the number of Avogadro times the atoms in a unit cell. To compare with experimental data the result should be divided by the number of unit formulas in the cell. If the structure is provided the division is performed internally and the result is in J/(K*mol)
 Parameters
t – a temperature in K
structure – the structure of the system. If not None it will be used to determine the numer of formula units
 Returns
Constant volume specific heat C_v

entropy
(t, structure=None)[source]¶ Vibrational entropy at temperature T obtained from the integration of the DOS. Only positive frequencies will be used. Result in J/(K*molc). A molc is the abbreviation of a molecell, that is, the number of Avogadro times the atoms in a unit cell. To compare with experimental data the result should be divided by the number of unit formulas in the cell. If the structure is provided the division is performed internally and the result is in J/(K*mol)
 Parameters
t – a temperature in K
structure – the structure of the system. If not None it will be used to determine the numer of formula units
 Returns
Vibrational entropy

get_interpolated_value
(frequency)[source]¶ Returns interpolated density for a particular frequency.
 Parameters
frequency – frequency to return the density for.

get_smeared_densities
(sigma)[source]¶ Returns the densities, but with a Gaussian smearing of std dev sigma applied.
 Parameters
sigma – Std dev of Gaussian smearing function.
 Returns
Gaussiansmeared densities.

helmholtz_free_energy
(t, structure=None)[source]¶ Phonon contribution to the Helmholtz free energy at temperature T obtained from the integration of the DOS. Only positive frequencies will be used. Result in J/molc. A molc is the abbreviation of a molecell, that is, the number of Avogadro times the atoms in a unit cell. To compare with experimental data the result should be divided by the number of unit formulas in the cell. If the structure is provided the division is performed internally and the result is in J/mol
 Parameters
t – a temperature in K
structure – the structure of the system. If not None it will be used to determine the numer of formula units
 Returns
Phonon contribution to the Helmholtz free energy

ind_zero_freq
[source]¶ Index of the first point for which the freqencies are equal or greater than zero.

internal_energy
(t, structure=None)[source]¶ Phonon contribution to the internal energy at temperature T obtained from the integration of the DOS. Only positive frequencies will be used. Result in J/molc. A molc is the abbreviation of a molecell, that is, the number of Avogadro times the atoms in a unit cell. To compare with experimental data the result should be divided by the number of unit formulas in the cell. If the structure is provided the division is performed internally and the result is in J/mol
 Parameters
t – a temperature in K
structure – the structure of the system. If not None it will be used to determine the numer of formula units
 Returns
Phonon contribution to the internal energy

zero_point_energy
(structure=None)[source]¶ Zero point energy energy of the system. Only positive frequencies will be used. Result in J/molc. A molc is the abbreviation of a molecell, that is, the number of Avogadro times the atoms in a unit cell. To compare with experimental data the result should be divided by the number of unit formulas in the cell. If the structure is provided the division is performed internally and the result is in J/mol
 Parameters
t – a temperature in K
structure – the structure of the system. If not None it will be used to determine the numer of formula units
 Returns
Phonon contribution to the internal energy