.. _nrlmolinput:

=====================================================
NRLMOL_INPUT.DAT: Controlling a calculation
=====================================================

The **NRLMOL_INPUT.DAT** is an auxiliary input file that allows setting of control parameters for calculation.  If it does not exist, then it will be 
created by the FLOSIC executable using default values.

The NRLMOL_INPUT.DAT with default values of parameters as of today (August 15, 2019) is given below. 

.. literalinclude:: /_static/input_files/nrlmolinput.file

A large number of entries related to calculation of certain properties are given as yes (``Y``) or no (``N``).
Note that certain calculations such as, for example, the calculation of joint density of states (``JNTDOSV``) is often useful only at the final converged geometry.

Most of the variables are already explained briefly in the NRLMOL_INPUT.DAT file. Below we add some comments on a few of them.

ATOMSPHV
-------------

Set to **Y** to calculate charge and spin charge in each inequivalent atom integrated over a sphere of specified  radius.

----------------------------------------------------

BASISV
-------------
 
This variable specifies which basis set is employed.  The ``'DEFAULT'`` basis is the NRLMOL Basis, optimized for the PBE functional

Other bases are available in the **basis.txt** file, found in the **basis** 
subdirectory. This file lists all the basis sets available.

The following bases are available:

+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21G                   | 6-31G-Blaudeau           | Ahlrichs_TZV          | Partridge_Uncontracted_1 |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21Gs                  | 6-31Gs                   | Ahlrichs_VDZ          | Partridge_Uncontracted_2 |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21GSP                 | 6-31Gs-Blaudeau          | Ahlrichs_VTZ          | Partridge_Uncontracted_3 |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21Gs_Polarization     | 6-31Gs_Polarization      | DZVP2                 | Partridge_Uncontracted_4 |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21ppG                 | 6-31Gss                  | DZVP                  | Saddlej                  |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 3-21ppGs                | 6-31Gss_Polarization     | GAMESS_PVTZ           | STO-2G                   |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311G                  | 6-31pGs                  | GAMESS_VTZ            | STO-3G                   |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311Gss                | 6-31ppG                  | Huzinaga_polarization | STO-3Gs                  |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311Gss_Polarization   | 6-31ppGs                 | IGLO-II               | STO-3Gs_Polarization     |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311pGs                | 6-31ppGss                | IGLO-III              | STO-6G                   |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311ppG2d2p            | Ahlrichs_Coulomb_Fitting | McLeanChandler_VTZ    | TZVP                     |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-311ppGss              | Ahlrichs_Polarization    | MIDI_Huzinaga         |                          |
+-------------------------+--------------------------+-----------------------+--------------------------+
| 6-31G                   | Ahlrichs_pVDZ            | MINI_Huzinaga         |                          |
+-------------------------+--------------------------+-----------------------+--------------------------+

The user only needs to specify the string preceding the *.basis* extension in the input file. For example, 
if the user wants to use 6-31G basis then he should replace :code:`'DEFAULT'` with :code:`'6-31G'`.

----------------------------------------------------------------------------------------------------------------------------

CALCTYPEV
-------------
 
Available choices:  

* **SCF-ONLY**: This choice is used when the user is not interested in an atomic geometry optimization. Atomic forces are not computed with this setting.
*  **CONJUGATE-GRADIENT**: Atomic geometry optimization is done using the conjugate-gradient algorithm.
*  **LBFGS** : ...WIP...

----------------------------------------------------------------------------------------------------------------------------

DIAG1V
-----------------------

This variable allows different diagonalization algorithms to use for  diagonalization of the Hamiltonian.

The options for this variable are:
   #.  DSGVX (LAPACKL: computes selected eigenvalues, and optionally eigenvectors). 
   #.  DSGVD (Default if matrix size is below 100).  Uses a divide and conquer algorithm to compute eigenvectors.
   #.  DSGV   (This is the slowest of the available)

----------------------------------------------------------------------------------------------------------------------------

DIAG2V
---------------------

This variable allows diagonalization of the Hamiltonian using packed storage format for memory savings. This is useful for large system sizes.
Available options are:
#. DSPGVX (LAPACK: computes selected eigenvalues, and optionally eigenvectors). 
#. DSPGVD (Default if matrix size is below 100).  Uses a divide and conquer algorithm to compute eigenvectors.
#.  DSPGV (QR- factorization. This is the slowest of the available) 

The option 1 (DSPGVD) is the fastest if all eigenvectors are required otherwise use the default 0. 

.. note:: 

   FLOSIC does not use **SCALAPACK**

----------------------------------------------------------------------------------------------------------------------------

POPULATIONV
--------------------------

When it is set to Y, Mulliken and Lowdin Population analysis calculations are run. Note that this is available only for spin polarized. 

----------------------------------------------------------------------------------------------------------------------------

RHOGRIDV
------------------------

When set to Y,  it will generate a CUBE file for visulaization of total and spin density (spin up - spin down).