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https://github.com/muammar/huckel

A program to calculate electronic spectrum at tight binding level
https://github.com/muammar/huckel

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A program to calculate electronic spectrum at tight binding level

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README 

        
huckel

======



As stated in the wikipedia`[0]`, The Hückel method or Hückel molecular orbital

method (HMO), proposed by Erich Hückel in 1930, is a very simple linear

combination of atomic orbitals molecular orbitals (LCAO MO) method for the

determination of energies of molecular orbitals of pi electrons in conjugated

hydrocarbon systems, such as ethene, benzene and butadiene. It is the

theoretical basis for the Hückel's rule. The extended Hückel method developed

by Roald Hoffmann is computational and three-dimensional and was used to test

the Woodward–Hoffmann rules. It was later extended to conjugated molecules such

as pyridine, pyrrole and furan that contain atoms other than carbon, known in

this context as heteroatoms.



Even if the tight-binding approach represents a crude approximation of

a chemical system, it can be very useful in order to sketch out some general

tendencies, and to elucidate the behavior of different classes of compounds.

This is particularly true since its extremely reduced computational cost allows

the treatment of very large systems. It is possible, therefore, to have an

insight into the behavior of the studied system in the limit of a large number

of atoms, that is usually impossible at the ab initio level`[1]`.



This is a python program that takes your MOLPRO output file, and from the

Cartesian coordinates, it forms a Huckel hamiltonian matrix to then give you

the eigenvalues to be plotted against the normalized eigenvalues ordinal

numbers as showed in `[1]`. It is also possible to delete desired Carbon atoms

by indicanting their respective numbers in the structure.



I'll be working in a generalization of the problem treated. More information

soon.



0. [https://en.wikipedia.org/wiki/H%C3%BCckel_method](https://en.wikipedia.org/wiki/H%C3%BCckel_method)

1.  M. El Khatib, S. Evangelisti, T. Leininger, and G. L. Bendazzoli, Phys. Chem. Chem. Phys., 2012, 14, 15666–76.



## Requirements



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



- Python.

- 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



Clone this repository:



```bash

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

```



Then you excute the program as follows:



```bash

$ python $PATH/huckel/huckel.py $input

```



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

if your molecule has the same internuclear distances, and to enter such value.

In the case that your carbon structure has different values, the program will

ask you for the interval of such distances. You can take a look at the

[`examples/`](https://github.com/muammar/huckel/tree/master/examples) directory

to more information regarding this.



Finally, a `huckel.dat` file will be created at the end of the execution that

you can plot using your favorite plotting software.



## Feedback?



You can send to me [suggestions, and improvements](https://github.com/muammar/centerfinder/issues).

They are very welcome.