:orphan:
 

.. index:: *LOCALIZATION
.. _*LOCALIZATION:

==============
\*LOCALIZATION
==============

Performs molecular orbitals localization using the Pipek-Mezey
criterion. The implementation uses an exponential parametrization and a
Trus region minimization method instead of the Edminston-Ruedenberg
algorithm. It works with the *C*\ :sub:`1`\ symmetry and for the occupied orbitals.


.. index:: .PRJLOC
.. _LOCALIZATION_.PRJLOC:

.PRJLOC
-------

Localization from projection analysis instead of Mulliken analysis. [Default: False]::

  .PRJLOC


.. index:: .OWNBAS
.. _LOCALIZATION_.OWNBAS:

.OWNBAS
-------

Calculate fragments in their own basis. For now it is the only option which can be
used with projection analysis option (.PRJLOC) [Default: False]::

  .OWNBAS

.. index:: .VECREF
.. _LOCALIZATION_.VECREF:

.VECREF
-------

First give number of fragments to project onto. Then for each fragment give
filename of MO coefficients and string specifying which orbitals will be
used in the projection (:ref:`orbital_strings`)::

  .VECREF
   3
   DFO1AT
   1..6
   DFH1AT
   1
   DFH2AT
   1


.. index:: .HESLOC
.. _LOCALIZATION_.HESLOC:

.HESLOC
-------

Define model of the Hessian [Default: FULL].

Use full Hessian::

  .HESLOC
   FULL

Use diagonal approximation of the Hessian. If using this approximation,
there is danger of converging to the stationary point instead of minima::

  .HESLOC
   DIAG

First the diagonal approximation of the Hessian will be used 
and after reaching convergence criterion the localization will 
switch to the construction of the full Hessian::

  .HESLOC
   COMB

.. index:: .CHECK
.. _LOCALIZATION_.CHECK:

.CHECK
------

This keyword can be used only in combination with .HESLOC = COMB.
The full Hessian will be calculated only at the last iteration.
This way one can check if the procedure converged to the minimum.


.. index:: .THFULL
.. _LOCALIZATION_.THFULL:

.THFULL
-------

Convergence threshold for the localization process. It applies on the functional
value of the localization criteria when full Hessian is calculated. It is used in 
.HESLOC = FULL scheme and in the second part of the .HESLOC = COMB scheme.
When not specified gradient criterion or criterion of the number of negative
eigenvalues equals zero will be used::

  .THFULL
   1.0D-13


.. index:: .THGRAD
.. _LOCALIZATION_.THGRAD:

.THGRAD
-------

Convergence threshold for the localization process. It applies on the gradient
of the localization functional. It is used in .HESLOC = FULL or DIAG scheme and in the
second part of the .HESLOC = COMB scheme. When not specified the functional value 
criterion or criterion of the number of negative eigenvalues equals zero will be used::

  .THGRAD
   1.0D-17


.. index:: .THDIAG
.. _LOCALIZATION_.THDIAG:

.THDIAG
-------

Convergence threshold for the localization process. It applies on the functional 
value of the localization criteria when diagonal Hessian is calculated.
It can be used with the .HESLOC = DIAG keyword.
If .HESLOC = COMB it is used to switch from the first to the second stage of the
convergence process::

  .THDIAG
   1.0D-05


.. index:: .SELECT
.. _LOCALIZATION_.SELECT:

.SELECT
-------

Select subset of MOs for localization (use :ref:`orbital_strings` syntax). 
Currently only Pipek-Mezey localization is implemented, therefore localize
only occupied orbitals. Localization of virtual orbitals is not recommended.

::

  .SELECT
   1..5


.. index:: .MAXITR
.. _LOCALIZATION_.MAXITR:

.MAXITR
-------

Maximum number of iterations. Default::

  .MAXITR
   100


.. index:: .PRINT
.. _LOCALIZATION_.PRINT:

.PRINT
------

Set print level. Default::

  .PRINT
   1