# Electric and Magnetic Static Fields¶

EField

Include a homogeneous, static, electric field in the z-direction (only possible for 0D, 1D or 2D periodic systems):

EField
Ez rval
{Unit [Volt/Angstrom | a.u. | Volt/Bohr | Volt/Meter]}
End

Ez
This option expects a real value which is the strength of the electric field.
Unit
(Default: Volt/Angstrom) This options specifies the unit of the electric field.

The static field is explicitly handled in the determination of the orbital coefficients, energy, and gradients. If you apply it to any other property, such as the NMR shielding tensor, dielectric function, solvation energy, etc., the result is probably not entirely correct. In case of doubt contact the SCM staff.

FuzzyPotential

Atomic (fuzzy cell) based, external, electric potential

FuzzyPotential
scale \$scale
a1 v1   ! atom with index a1 gets potential coefficient v1 (a.u.)
a2 v2   ! atom a2 gets potential v2
...
End

scale
Overall scaling factor to be applied.

If an atom is not in the list it gets a coefficient of zero. The potential of an atom is its number ($$v_i$$) as specified on input times its fuzzy cell

$V(r) = \sum_i^\text{atoms} v_i \mathcal{P}_{i,U} (r)$

using the same partition function $$\mathcal{P}$$ as for the BeckeGrid. A partition function (or fuzzy cell) of an atom is close to one in the neighborhood of this atom.

The sign convention is: negative is favorable for electrons. (Unit: a.u.)

BField

The effect of a magnetic filed can be approximated by the following potential: $$\mu_B \vec{\sigma}_i \vec{B}$$, where $$\mu_B$$ is the Bohr magneton, $$\vec{\sigma}_i$$ are the Pauli matrices and $$\vec{B}$$ is the magnetic field. For Spin-unrestricted collinear calculations, the spin is assumed to be aligned with the z-axis.

BField
Bx rval
By rval
Bz rval
End

Bz,By,Bz
(Units: Tesla) X,Y and Z components of the magnetic field.