Fix labels in plot_thermodynamic_properties

[ab5424]

The labels seem to be incorrect (see

pymatgen/pymatgen/phonon/dos.py

Lines 229 to 236 in 72d336d

	def internal_energy(self, t, structure=None):
	"""
	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/mol-c. A mol-c is the abbreviation of a mole-cell, 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

and

pymatgen/pymatgen/phonon/dos.py

Lines 263 to 270 in 72d336d

	def helmholtz_free_energy(self, t, structure=None):
	"""
	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/mol-c. A mol-c is the abbreviation of a mole-cell, 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

respecitvely)

[mkhorton]

Thanks for noticing and submitting the fix @ab5424!