centerfinder

This python script intends to look for localized molecular orbitals (LMO) near to atoms based on the center of charges and prepare a MOLPRO input file in order to perform later incremental calculations as stated in H. Stoll, Chem. Phys. Lett., 1992, 19. This is normally a very tedious work to be done by hand, and it's there when centerfinder comes to help.

It reads your MOLPRO output file, and then it extracts coordinates and center of charges to then print which LMO are in between which atoms in the molecule. In your MOLPRO output file, a localization calculation must have been done beforehand. Take into account that your calculation has to be done using the symmetry,nosym; card in MOLPRO. On the other hand, you have to save your LMO to the record 2103.2. Below, an example of the locali block in MOLPRO to be used to run this program:

{locali;
save,2103.2;
core,10;
group,28.1,31.1,-34.1;
group,11.1,-27.1,29.1,30.1;
}

Note: The script prepares two input files with the rotations needed to do one- and two- body interactions, as well as the CASSCF and CCSD input. I will generalize more this script in the coming time.

Requirements

In order to run this script, you need to install in your system:

• Python 2.7 (I am porting this to work with Python >3)
• NumPy.
• SciPy.

You can use pip to install them or the package manager of your favorite Linux distribution or Mac OS X.

How to use it

Installation and execution

Clone this git repository:

$ git clone https://github.com/muammar/centerfinder.git

Then you excute the program as follows:

$ python $PATH/centerfinder/centers.py $input

Where $input is the name of your MOLPRO output file. The program will ask you:

1. Number of CORE MOs used in your calculation for doing the localization.

• Number of Localized Molecular orbitals.

Then, for the CASSCF calculation section it will ask you:

3. Number of CLOSED MOs.

• Number of FROZEN MOs.
• Number of OCCUPIED MOs.
• The wavefunction in the format: wf,#electrons,Sym,Multiplicity.
• Atoms to be discarded by symmetry reasons.

Note: The default answers are NO so you can just press enter and the program will continue.

Finally, a molpro.in and molpro2.in files will be created at the end of the execution. Please note that in MOLPRO you can only run maximum of about 100 calculations per input file.

The input file created is too long, how can I split it?

If you are using linux, there is a very nice command called split (man split for more information). So, if you have one input file created by centerfinder that has more than 500 lines and you want to split it in 2 parts, you can do:

$ split -l 250 molpro2.in

and you will split molpro2.in in two files containing 250 lines each one.

Please note that you have to check that every MOLPRO block when splitting is correctly done. I am thinking in adding another program that let you do this instead of using split.

How do I check that this input file was correctly generated?

I suggest you to make the one body calculations given in molpro.in and make an analysis of the energies and check if the LMO are well assigned (using any of the available molecular visualizers). If after checking your one body results you find they are fine, so you are good to go. Actually, the two body interactions are built from the one body ones. The script proceeds as follows: a) it calculates the possible combinations; b) it asks you if you want to discard atoms to not be taken into account in the two body interaction part; c) and finally it writes molpro2.in.

The onebody calculations are wrong, the LMO doesn't match when I plot them using a molecular visualizer. What can I do?.

There are 4 parameters you can change in the following lines:

• atnearat=np.argwhere((distances > 2.3) & (distances < 2.7))
• lmonat=np.argwhere((dcoordcoc > 0.5) & (dcoordcoc < 2.0))

If you do something wrong, you can revert the changes by doing:

$ git checkout $PATH/centerfinder/centers.py

How to update it?

To update this program, just do a git pull in your $PATH/centerfinder/ folder.

Feedback?

This is my first program, if it can be called like that, written in python. So, I'm sure it is not optimal at all. However, you can send to me suggestions, and improvements. They are very welcome.