# counterpoise

Perform an energy calculation with counterpoise corrections.

To run a counterpoise calculation, we specify the fragments of the system using fragment subcommands. Each fragment requires the indices of atoms to be specified via atoms, and optionally, one can also specify charge and spin of each fragment. The atom indices are not required for the last fragment, as they can be deduced from all previous fragments. Each atom should appear exactly once in one fragment.

An example counterpoise-correction calculation on water dimer might be run using:

counterpoise(
structure( xyz =
[ [O, -7.35477,  1.81815, -0.05747],
[H, -6.91635,  1.88742,  0.82758],
[H, -7.26200,  0.86404, -0.30635],
[O, -4.29190,  0.22949,  0.60862],
[H, -4.01817,  0.87304,  1.30970],
[H, -4.40650,  0.78270, -0.20462]]
)
fragment(
atoms = [1:3]
)
fragment(
atoms = [4:6]
)
dft(
xc = B3LYP
ao = '6-31G*'
df = 'Def2-SVP-JKFIT'
)
)

This command can appear in the global context.

### Options

name

Specify the name of a set of results.

This option is deprecated.

• The type is string
• There is no default value.
print_level

Print level.

• The type is int
• There is no default value.
• The value must be one of:
• -2 - No output
• -1 - Minimum output
• 0 - Output that doesn't scale with system size
• 1 - Output that scales linearly with system size
• 2 - (Debugging) output that scales quadratically with system size
• 3 - (Debugging) output that scales cubically with system size