oqp.library.openqp_dftb
=======================

.. py:module:: oqp.library.openqp_dftb

.. autoapi-nested-parse::

   .. code-block:: text

      OpenQP runtime adapter for the optional OpenQP-DFTB backend.



Attributes
----------

.. autoapisummary::

   oqp.library.openqp_dftb.HA_TO_WAVENUMBER
   oqp.library.openqp_dftb.FINE_STRUCTURE


Classes
-------

.. autoapisummary::

   oqp.library.openqp_dftb.OpenQPDFTBAdapter


Functions
---------

.. autoapisummary::

   oqp.library.openqp_dftb.dftb_soc


Module Contents
---------------

.. py:class:: OpenQPDFTBAdapter(mol)

   .. code-block:: text

      Make OpenQP-DFTB look like a normal OpenQP energy/gradient provider.


   .. py:attribute:: mol


   .. py:attribute:: config


   .. py:attribute:: dftb


   .. py:attribute:: natom


   .. py:attribute:: nstate


   .. py:method:: energy()

      .. code-block:: text

         Return an OpenQP-style state-energy array and update molecule data.



   .. py:method:: reference()

      .. code-block:: text

         Return the DFTB reference energy in the same shape as SCF reference().



   .. py:method:: excitation(_ref_energy=None)

      .. code-block:: text

         Return DFTB total state energies after a reference-style call.



   .. py:method:: gradient(states)

      .. code-block:: text

         Return an OpenQP-style gradient array indexed by state number.



   .. py:method:: states_overlap(xyz_old, xyz_new, mo_old, mo_new, x_old, x_new, *, noca, nocb, multiplicity, tlf_order=2)

      .. code-block:: text

         Cross-geometry MRSF/SF state overlap via libopenqp_dftb_c.

         All matrix inputs are FORTRAN-FLAT 1-D arrays (i.e. tag.ravel() of the
         native-convention tags). Returns (overlap_mo_tag, states_overlap_tag)
         in the same native tag layout (transpose view of the Fortran matrices).



   .. py:method:: soc_matrix(mo, x_singlet, x_triplet, *, noca, nocb)

      .. code-block:: text

         Raw one-center MRSF SOC matrix (no alpha^2/2) via libopenqp_dftb_c.

         Inputs are Fortran-flat 1-D arrays; returns (hsoc_re, hsoc_im) as
         (dim, dim) numpy arrays in the GAMESS state ordering, where the
         row/column index layout matches the native soc_mrsf convention.



.. py:data:: HA_TO_WAVENUMBER
   :value: 219474.6313708


.. py:data:: FINE_STRUCTURE
   :value: 0.0072973525693


.. py:function:: dftb_soc(mol)

   .. code-block:: text

      Standalone SOC driver for method=dftb (mirror of the native compute_soc).

      Runs the MRSF response for both target multiplicities from the same ROKS
      reference, builds the one-center SOC matrix, diagonalizes
      diag((E - e0) * ha2wn) + hsoc * (alpha^2/2 * ha2wn) in numpy, and fills the
      same OQP:: tags the native soc_mrsf produces (soc_eval in cm^-1 relative to
      the lowest MCH excitation; soc_hsoc_* raw, without the alpha^2/2 prefactor).