ODIN Project
============

This project contains Fortran 90 source code for the ODIN program. The code constructs the overlap matrix for the DFTB method and prints the results to a file (oversqr.dat). The code also works for short distances, below the first entry of the Slater-Koster files. Note that special Slater-Koster files are required in order for the code to work properly. Slater-Koster files tabulate the overlap as a function of distance. For many existing files (for example most of the files found on dftb.org) the real data values start only at some minimal distance which is normally never sampled in simulations. The values for shorter distances are just dummy values (for example 20*1.0). In order to generate valid Slater-Koster files you may use the https://github.com/dftbplus/skprogs toolchain and set GridStart equal to GridSeparation. 

Example input
-------------
'geo.gen'		     | Structure in DFTB gen format
'/home/niehaus/sk/mio-0-1/'  | Prefix for Slater-Koster files
'-'                          | Separator
'.skf'                       | Suffix
1 2                          | Max. angular momentum (s=1, p=2, d=3) for each species
                             | order like in .gen file
			     
Usage
-----
odin < odin.inp 

Directory structure:
--------------------
- src/         Contains all source code files (*.f90, *.f)
- Makefile     Build instructions

The main program file is: src/odin.f90

How to Compile:
---------------
1. Open a terminal.
2. Change to the directory above src/ (where the Makefile is located).
3. Run:

   make

This compiles the program and produces an executable called 'odin'.

How to Install:
---------------
To install the executable system-wide (requires sudo):

   sudo make install

This installs the binary to /usr/local/bin by default.

To install to a custom location:

   make install PREFIX=/path/to/your/directory

For example, to install in your local bin:

   make install PREFIX=~/bin

Make sure your install location is in your PATH if you want to run 'odin' directly.

Cleaning Up:
------------
To remove object files and the executable:

   make clean

Requirements:
-------------
- A Fortran compiler (e.g., gfortran)
- GNU make

Tested with:
- gfortran 10.2
- GNU Make 4.3