Energy Terms and Functionals#

This page lists the energy terms and functionals that have been implemented. They can be included in a list of energy terms in the terms argument that goes into the initialization of a System object.

Take the following for example

terms = [IonIon, IonElectron, Hartree, WangTeter, PerdewBurkeErnzerhof]
...
system = System(box_vecs, shape, ions, terms)

Note that apart from the IonIon and IonElectron functions, the other functions must only take in inputs of box_vecs and den, which represent the lattice vectors and elecron density respectively, i.e. functional(box_vecs, den).

For example, the Xu-Wang-Ma functional was implemented to take in an additional argument that acts as a functional parameter, i.e. XuWangMa(box_vecs, den, kappa). A simple way to handle this is to use lambda functions.

terms = [IonIon, IonElectron, Hartree, lambda bv, n: XuWangMa(bv, n, 0), PerdewZunger]
...
system = System(box_vecs, shape, ions, terms)

Some kinetic functionals are represented by classes that inherit from the torch.nn.Module class, in which case it is their .forward() method that should be included in the list of terms. For example,

pg = PauliGaussian()
pg.set_PGSLr()
terms = [IonIon, IonElectron, Hartree, pg.forward, PerdewBurkeErnzerhof]
...
system = System(box_vecs, shape, ions, terms)

Energy Terms and Functionals#

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