nanotools.energy module

This module defines the Energy class.

class nanotools.energy.Energy(esr=None, ebg=None, ebs=None, edh=None, exc=None, evxc=None, etot=None, efermi=None, eigenvalues=None, efree=None, entropy=None, forces=None, forces_return=False, stress=None, stress_return=False, frc_t=None, frc_s=None, frc_vnl=None, frc_veff=None, frc_sr=None, frc_vna=None, frc_vdh=None, frc_rpc=None, edftd3=None, frc_dftd3=None, stress_dftd3=None, include_dftd3=False, dftd3_kwargs: dict = NOTHING)[source]

Bases: Base

Energy class.

The Energy class stores energy data. It is typically empty before a calculation. It gets overwritten during a calculation.

esr

esr is the short-range energy. Example:

esr = energy.esr

Type:: pint.registry.Quantity

ebs

ebs is the band structure energy. Example:

ebs = energy.ebs

Type:: pint.registry.Quantity

edh

edh is the delta Hartree energy. Example:

edh = energy.edh

Type:: pint.registry.Quantity

efermi

efermi is the Fermi energy. Example:

efermi = energy.efermi

Type:: pint.registry.Quantity

etot

etot is the total energy. Example:

etot = energy.etot

Type:: pint.registry.Quantity

evxc

evxc is the exchange-correlation potential energy. Example:

evxc = energy.evxc

Type:: pint.registry.Quantity

exc

exc is the exchange-correlation energy. Example:

exc = energy.exc

Type:: pint.registry.Quantity

eigenvalues

eigenvalues is a three-dimensional array containing the Kohn-Sham energies (the eigenvalues of the Kohn-Sham equation). The dimensions are the following: bands, k-point, spin. Example:

eigenvalues = energy.eigenvalues

Type:: pint.registry.Quantity

forces

forces is a two-dimensional array containing the atomic forces (as calculated by the Hellman-Feynman theorem). Example:

forces = energy.forces

Type:: pint.registry.Quantity

forces_return

If True, the forces are computed and written to energy.forces. They are not computed otherwise. Example:

energy.forces_return = True

Type:: bool

stress

stress is a two-dimensional array containing the stress tensor (as calculated by the Hellman-Feynman theorem). Example:

stress = energy.stress

Type:: pint.registry.Quantity

stress_return

If True, the stress tensor is computed and written to energy.stress. It is not computed otherwise. Example:

energy.stress_return = True

Type:: bool

edftd3

Grimme’s DFT-D3 energy. It is evaluated with ASE’s DFTD3 calculator. For additional details on the methods, please visit the Mulliken Center’s website.

Type:: pint.registry.Quantity

frc_dftd3

Grimme’s DFT-D3 forces.

Type:: pint.registry.Quantity

stress_dftd3

Grimme’s DFT-D3 stress.

Type:: pint.registry.Quantity

include_dftd3

Grimme’s DFT-D3 switch. If True, include D3 dispersion corrections in energy, forces and stress. Do nothing otherwise.

Type:: bool

get_cbm()[source]

Returns the conduction band maximum.

If partially occupied bands are detected, as in metals, then the function returns None.

Returns:: conduction band maximum
Return type:: float

get_free_energy()[source]: Returns the free energy.

get_total_energy()[source]: Returns the total energy.

get_vbm()[source]

Returns the valence band maximum.

If partially occupied bands are detected, as in metals, then the function returns None.

Returns:: valence band maximum
Return type:: float

ismetal()[source]

Determines whether the band structure is metallic.

The band structure is metallic if some bands are partially filled at zero temperature. The function determines band occupancy based on the Fermi level. Note that the Fermi level may cut the VBM or CBM of semiconductors or insulators depending on the occupation scheme and k-sampling mesh.

Returns:: True if metallic, False otherwise
Return type:: bool

set_stress_return(stress_return)[source]

Sets stress_return attribute.

If stress_return is True, then forces_return is also set to True.

Parameters:: stress_return (bool) – stress_return value