.. tip::
    All input files can be downloaded: :download:`Files <https://zhjun-sci.com/qbics/input_library/keywords-thermo.tar.gz>`.

thermo
=========

.. contents::
   :local:

This keyword defines the parameters for thermodynamic analysis based on frequency calculation results.

Options
------------

.. option:: temp

   .. list-table::
      :stub-columns: 1
      :widths: 5 20
   
      * - Value
        - A real number
      * - Default
        - ``298.15``
    
   The temperature (in Kelvin) for thermodynamic analysis. The default value is ``298.15`` K. 
   
.. option:: pressure

   .. list-table::
      :stub-columns: 1
      :widths: 5 20
   
      * - Value
        - A real number
      * - Default
        - ``1.``
    
   The pressure (in atm) for thermodynamic analysis. The default value is ``1.0`` atm.

.. option:: point_group_delta

   .. list-table::
      :stub-columns: 1
      :widths: 5 20
   
      * - Value
        - A real number
      * - Default
        - ``0.01``
    
   A threshold to determine the point group of the molecule. The default value is ``0.01``. The smaller ``point_group_delta``, the more accurate the symmetry point group will be determined. However, a very small value may lead to failure in point group determination. If you encounter such problem, please increase this value gradually (e.g., to ``0.1``).

Theoretical Background
-------------------------



Input Examples
--------------------

Example: XX
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For the complex GeH\ :sub:`3`\ F-NCH, we can do EDA calculation by the following input:

.. code-block:: bash
    :linenos:
    :caption: eda-1.inp

    mol
       Ge      0.00000000      0.00221863     -0.79935317
        H      0.00000000      1.48645043     -0.40384625
        H      1.28514604     -0.74161126     -0.40477816
        H     -1.28514603     -0.74161126     -0.40477816
        F      0.00000000      0.00108752     -2.56116087
        C      0.00000000     -0.00225138      3.35662076
        H      0.00000000     -0.00220444      4.43604901
        N      0.00000000     -0.00207825      2.20326200    
    end

    basis
        def2-svp
    end
    
    scf
        charge  0
        spin2p1 1
        type    U # For EDA calculations, this must be added explicitly.
    end
     
    grimmedisp
        type bj
    end
    
    eda
        type tso # You can also change it to: gks
        frag 0 1 1-5  # Define GeH3F.
        frag 0 1 6-8  # Define HCN.
    end
    
    task
        eda b3lyp
    end
    
The atom indices are shown below:

.. figure:: figs/basinfo-1.jpg

The results are:

.. tabs::

   .. tab:: TSO-EDA Results

      .. code-block:: bash
          :linenos:
          :caption: eda-tso.out

          WITH BSSE correction:
          Electrostatic interaction energy:                  -4.98 kcal/mol
          Exchange-correlation interaction energy:            4.22 kcal/mol
          Polarization interaction energy:                   -0.62 kcal/mol
          Charge transfer interaction energy:                -1.31 kcal/mol
          Grimme's dispersion interaction:                   -1.58 kcal/mol
          ----------------------------------------------------------------
          Total interaction energy:                          -4.27 kcal/mol

   .. tab:: GKS-EDA Results

      .. code-block:: bash
          :linenos:
          :caption: eda-gks.out
      
          WITH BSSE correction:
          Electrostatic interaction energy:                  -6.22 kcal/mol
          Exchange interaction energy:                       -9.64 kcal/mol
          Repulsion interaction energy:                      15.94 kcal/mol
          Polarization interaction energy:                   -2.52 kcal/mol
          Correlation interaction energy:                    -0.24 kcal/mol
          Grimme's dispersion interaction:                   -1.58 kcal/mol
          ----------------------------------------------------------------
          Total interaction energy:                          -4.27 kcal/mol

We can see that the total interaction energies (with or without BSSE) are the same for both TSO-EDA and GKS-EDA methods, but components are different. As mentioned, Qbics recommends **TSO-EDA** for calculations. This complex is stabilized by ``Electrostatic interaction eneregy``, which is compatible with the chemical intuition that it is stabilized by sigma-hole.