onsite_energy_modifier

onsite_energy_modifier(is_double: bool = False, phase: bool = False, **kwargs) → partial

Modify the onsite energy, e.g. to apply an electric field

Parameters:

is_doublebool

Requires the model to use double precision floating point values. Defaults to single precision otherwise.

phasebool

Define the phase of the reciprocal space so that the different eigenvectors have the same guage.

Notes

The function parameters must be a combination of any number of the following:

energyndarray

The onsite energy.

x, y, zndarray

Lattice site position.

sub_idsupport.alias.AliasIndex

Sublattice identifier: can be checked for equality with sublattice names specified in Lattice. For example, energy[sub_id == 'A'] = 0 will set the onsite energy only for sublattice A sites.

sitesSites

Helper object. Can be used instead of x, y, z, sub_id. See Sites.

The function must return:

ndarray

A modified potential argument or an ndarray of the same dtype and shape.

Examples

def wavy(a, b):
    @pb.onsite_energy_modifier
    def f(x, y):
        return np.sin(a * x)**2 + np.cos(b * y)**2
    return f

model = pb.Model(
    ... # lattice, shape, etc.
    wavy(a=0.6, b=0.9)
)