EPLF

• Dependencies
• Using EPLF
• References

Computes the Electron Pair Localization Function.

Dependencies

• Python3
• resultsFile : https://gitlab.com/scemama/resultsFile
• IRPF90 : http://irpf90.ups-tlse.fr
• GFortran or Intel Fortran

resultsFile and IRPF90 can both be installed with pip.

python3 -m pip install resultsFile
python3 -m pip install irpf90

./configure should detect suitable defaults for your system. You can update the make.config file if you want. It is important to give the Fortran compiler the option to accept infinitely long lines (with gfortran, the option is -ffree-line-length-none). The configure script will also create a file $HOME/.eplfrc that you will need to source before running the program.

Using EPLF

GAMESS or Gaussian can be used to produce the wave function. With Gaussian, the following keywords are required:

# GFPRINT pop=Full 6d 10f

Go into the test directory and execute the following commands to make a test run with an Gaussian output file.

1. Run the eplf_input.py script to convert the output file into an EZFIO directory containing all the data required for the computation:

   eplf_input.py c2h.out

   The c2h.out.ezfio directory is produced.

2. Edit the parameters by running eplf_edit.py

   eplf_edit.py c2h.out.ezfio

   The editor defined with the $EDITOR environment variable will open and let you change the parameters. To compute the density and the EPLF, just add an X character between the brackets next to eplf and density:

   ( ) density ->   (X) density
   ( ) eplf    ->   (X) eplf
   

3. Run the program to compute the data and save it in the EZFIO directory

   eplf c2h.out.ezfio

   If the program is compiled with MPI, run

   mpirun eplf c2h.out.ezfio

4. Now you can convert the data into cube files as:

   to_cube.py c2h.out.ezfio density
   to_cube.py c2h.out.ezfio eplf

   The parameters of the grid can be changed by first clearing the data, and the updating the grid parameters. This can be done with eplf_edit.py by un-commenting the lines clear(all) and edit(grid_parameters).

References

Scemama, A., Chaquin, P., Caffarel, M. (2004). "Electron pair localization function: A practical tool to visualize electron localization in molecules from quantum Monte Carlo data". J. Chem. Phys. 121 (4), 1725–1735. doi:10.1063/1.1765098

Scemama, A., Caffarel, M., Chaudret, R., & Piquemal, J.-P. (2011), "Electron Pair Localization Function (EPLF) for Density Functional Theory and ab Initio Wave Function-Based Methods: A New Tool for Chemical Interpretation". J. Chem. Theory Comput. 7 (3), 618–624. doi:10.1021/ct1005938