mirror of
https://github.com/QuantumPackage/qp2.git
synced 2024-11-07 05:53:37 +01:00
65 lines
1.8 KiB
ReStructuredText
65 lines
1.8 KiB
ReStructuredText
Natural orbitals
|
||
================
|
||
|
||
Summary
|
||
-------
|
||
|
||
To produce state-average natural orbitals, run ::
|
||
|
||
qp_run save_natorb file.ezfio
|
||
|
||
The |MOs| will be replaced, so the two-electron integrals and the wave
|
||
function are invalidated as well.
|
||
|
||
|
||
|
||
Extracting natural orbitals
|
||
---------------------------
|
||
|
||
Once obtained the near |FCI| wave function, one can obtain many
|
||
quantities related to it. One of these quantities are the natural
|
||
orbitals which have the property of diagonalizing the one-body
|
||
density matrix:
|
||
|
||
.. math::
|
||
|
||
\rho_{ij} = \delta_{ij}
|
||
|
||
where the element of the one-body density matrix :math:`\rho_{ij}` is
|
||
defined as:
|
||
|
||
|
||
.. math::
|
||
|
||
\rho_{ij} = \langle \Psi | \left( a^{\dagger}_{j,\alpha} a_{i,\alpha} + a^{\dagger}_{j,\beta} a_{i,\beta} \right) | \Psi \rangle
|
||
|
||
|
||
These orbitals are in general known to be better than the usual |HF|
|
||
|MOs| as they are obtained from a correlated wave function. To use these
|
||
orbitals for future calculations, one has to replace the current |MOs|
|
||
by the natural orbitals. To do so, just run:
|
||
|
||
.. code::
|
||
|
||
qp_run save_natorb file.ezfio
|
||
|
||
|
||
Hands on
|
||
--------
|
||
|
||
.. important::
|
||
|
||
As the |MOs| are changed, for the sake of coherence of future
|
||
calculations, the :ref:`save_natorb` program *automatically removes the
|
||
current wave function* stored in the |EZFIO| database and replaces
|
||
it by a single Slater determinant corresponding to a |HF| occupation
|
||
of the new spin orbitals. Also, all the keywords to read the one-
|
||
and two-electron integrals on the |MO| basis are set to ``None`` in
|
||
order to be sure to avoid reading integrals incompatible with the
|
||
current set of |MOs|.
|
||
|
||
.. seealso::
|
||
|
||
The documentation of the :ref:`save_natorb` program.
|
||
|