# wannier keywords

Wannier function calculator

## wannier.bandi

Band index range for the inner energy window. If wannier.bandi is given,
wannier.innwin will be generated using wannier.bandi. If both
wannier.bandi and wannier.innwin aren\'t set, RESCU will compute the
Wannier function of all bands fully comprised in the outer window.

**type**: `array`

**size**: `[1,2]`

**example**: `wannier.bandi = [2,6]`

## wannier.innwin

The inner energy window, also know as the frozen window, determines
which Bloch states to be preserved identically in the projected
manifold. If wannier.bandi, wannier.innwin will be generated using
wannier.bandi. If both wannier.bandi and wannier.innwin aren\'t set,
RESCU will compute the Wannier function of all bands fully comprised in
the outer window.

**type**: `array`

**size**: `[1,2]`

**example**: `wannier.innwin = [-0.4 -0.1]`

## wannier.outwin

The outer energy window determines which Bloch states are included in
the projected manifold. The states comprised in the outer window but not
the inner window can be discarded such as to yield a maximally smooth
subspace for the Wannier function generation. If wannier.outwin isn\'t
set, RESCU will set it equal to the interval given by wannier.bandi and
wannier.innwin.

**type**: `array`

**size**: `[1,2]`

**example**: `wannier.outwin = [-0.4 -0.1]`

## wannier.maxit

Maximal number of iterations (used during the subspace smoothing
procedure and the spread functional optimization).

**type**: `scalar`

**default**: `100`

**example**: `wannier.maxit = 50`

## wannier.mixbeta

Mixing fraction of the Wannier function calculator (used during the
subspace smoothing procedure).

**type**: `scalar`

**default**: `0.5`

**example**: `wannier.mixbeta = 0.45`

## wannier.niterSD

Number of steepest-descent iterations prior to the conjugate gradient
algorithm during the spread functional optimization.

**type**: `scalar`

**default**: `1`

**example**: `wannier.niterSD = 1`

## wannier.omgTol

Optimization tolerance. The optimization procedure will stop once the
spread functional changes by less than the prescribed tolerance (used
during the subspace smoothing procedure and the spread functional
optimization). The tolerance is relative, which means for example that
if wannier.omgTol = 1e-4 the calculation will stop once the functional
is precise to 4 digits.

**type**: `scalar`

**default**: `1e-05`

**example**: `wannier.omgTol = 1e-4`

## wannier.optAlgo

Algorithm employed to perform the spread function minimization. SD and
CG stand for steepest-descent and conjugate gradient respectively.

**type**: `string`

**default**: `1e-05`

**allowed**: `'SD','CG'`

**example**: `wannier.optAlgo = 'CG'`

## wannier.orbi

Array containing the indices of the orbitals used to construct an
initial guess for the maximally localized Wannier gauge.

**type**: `array`

**default**: `1e-05`

**size**: `[inf,1]`

**example**: `wannier.orbi = [1 3:5]`

## wannier.sdalpha

Step scaling for the steepest-descent algorithm (used during the spread
functional optimization). 0.5 is usually stable, 1 is marginally stable.

**type**: `scalar`

**default**: `0.5`

**example**: `wannier.sdalpha = 0.5`

## wannier.shiftEf

Shift the energy windows by the Fermi energy, i.e. the energy windows
are relative to the Fermi energy.

**type**: `scalar`

**default**: `false`

**allowed**: `true,false`

**example**: `wannier.shiftEf = true`

## wannier.status

Compute Wannier functions if wannier.status = true.

**type**: `scalar`

**default**: `false`

**allowed**: `true,false`

**example**: `wannier.status = true`
