# population

Perform population analysis. For example:

dft(
structure(molecule = water)
xc = PBE
ao = DZP
)
population()


The source of the density matrix can be specified using the load option, and the type of analysis using type:

foo := dft(
structure(molecule = water)
ao = DZP
xc = PBE
)
population(
method = lowdin
)


This command can appear in the global context.

### Options

bond_order

Calculate bond order corresponding to the specified population method. Not all localization methods support bond-order analysis.

• The type is bool
• The default is false
df

Only valid for stockholder charges.

Density fitting basis name. This basis is used to fit products of the form $$|ij)$$ where $$i$$ and $$j$$ are occupied molecular orbitals.

Note: the input value must match exactly the name of the basis set file in the basis directory.

• The type is string-lowered
• The default is Ahlrichs Coulomb Fitting
iao_version

Specify the version of IAOs to be constructed.

• The type is string
• The default is standard
• The value must be one of:
• standard - Use the standard definition of IAOs. See this paper for details.
• simplified - Use the simplified definition of IAOs. See this paper for details.
• economical - Use the economical IAOs. This is based on the simplified IAOs, but without the orthonormalization of the depolarized MOs.
load

Name of result set from which to load the density matrix and basis set.

This option is mandatory.

• The type is string
• The default is previous
method

Specify the type of population analysis to perform.

• The type is string
• The default is mulliken
• The value must be one of:
• mulliken - Mulliken population analysis
• lowdin - Löwdin population analysis
• iao - Knizia's IAO population analysis
• stockholder - Variational Hirshfeld (or stockholder) charges
minao

Specify the MINAO basis for making the IAOs. The MINAO basis that should be used depends to the basis used in loaded result set. For DFT and HF calculations use the cc-pVTZ-MINAO basis. For xTB calculations use the GFN-xTB-MINAO basis.

• The type is string-lowered
• The default is cc-pVTZ-MINAO
mo_weights_on_atoms

Whether to compute atomic contributions to each molecular orbital. This calculation is done using Löwdin population analysis.

• The type is bool
• The default is false
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