#### GammaOnly

Do just the Γ point (k=0) rather than full k-integration.

#### NKPoint=N

Do approximately N k-points.

#### CellRange=N

Go out N Bohr in each direction in setting up image cells.

#### NCellMin=N

Include at least N cells.

#### NCellMax=N

Include at most N cells in any part of the calculation.

#### NCellDFT=N

Include at least N cells in DFT XC quadrature. NCellXC is a synonym for this option.

#### NCellK=N

Include at least N cells in exact exchange. By default, if exact exchange is included, then this is twice the number of cells used for overlap-related quantities and XC quadrature.

Periodic systems are specified with a normal molecule specification for the unit cell. The only additional required input are one, two or three translation vectors appended to the molecule specification (with no intervening blank line), indicating the replication direction(s). For example, the following input specifies a one-dimensional PBC single point energy calculation for neoprene:

# PBEPBE/6-31g(d,p)/Auto SCF=Tight
neoprene, -CH2-CH=C(Cl)-CH2- optimized geometry
0 1
C,-1.9267226529,0.4060180273,0.0316702826
H,-2.3523143977,0.9206168644,0.9131400756
H,-1.8372739404,1.1548899113,-0.770750797
C,-0.5737182157,-0.1434584477,0.3762843235
H,-0.5015912465,-0.7653394047,1.2791284293
C,0.5790889876,0.0220081655,-0.3005160849
C,1.9237098673,-0.5258773194,0.0966261209
H,1.772234452,-1.2511397907,0.915962512
H,2.3627869487,-1.0792380182,-0.752511583
Cl,0.6209825739,0.9860944599,-1.7876398696
TV,4.8477468928,0.1714181332,0.5112729831

The final line specifies the translation vector. Note that it specifies TV as the atom symbol.

The following molecule specification could be used for a two-dimensional PBC calculation on a graphite sheet:

0 1
C 0.000000 0.000000 0.000000
C 0.000000 1.429118 0.000000
TV 2.475315 0.000000 0.000000
TV -1.219952 2.133447 0.000000

Here is the molecule specification that could be used for a three-dimensional PBC calculation on gallium arsenide:

0 1
Ga 0.000000 0.000000 0.000000
Ga 0.000000 2.825000 2.825000
Ga 2.825000 0.000000 2.825000
Ga 2.825000 2.825000 0.000000
As 1.412500 1.412500 1.412500
As 1.412500 4.237500 4.237500
As 4.237500 1.412500 4.237500
As 4.237500 4.237500 1.412500
TV 5.650000 0.000000 0.000000
TV 0.000000 5.650000 0.000000
TV 0.000000 0.000000 5.650000