#
`PI`

The normal density matrix is composed of atomic orbitals, that is *s*,
*p*_{x}, *p*_{y} and *p*_{z}. `PI` allows the user to see how each atom-atom interaction
is split into *σ*, *π*,
and *Δ*
bonds. The
resulting "density matrix" is
composed of the following basis-functions: *s-σ,
p-σ, p-π, d-σ,
d-π, d-δ*.
The on-diagonal terms give the hybridization
state, so that an sp^{2} hybridized system would be represented as
*s-σ*:
1.0, *p-σ*:
2.0, *p-π*:
1.0.