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32 votes
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Where is the extended Hückel method (EHM) still used today?

In an era of ab initio methods and many-body methods like the $GW$, there is not too much room for methods like the extended Hückel model to be the main method in any particular field of materials ...
epalos's user avatar
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18 votes

State of the art in computational materials design

After a little research I found a great article [1], which provides a good overview to what I asked above in Figure 2. Summarising in a table: Method effort reliability system size Interatomic ...
Michael F. Herbst's user avatar
18 votes

Where is the extended Hückel method (EHM) still used today?

One area where the extended-Huckel method continues to see use is to form the initial guess for an SCF calculation or even just a more accurate semi-empirical method. While most electronic structures ...
Tyberius's user avatar
  • 15.5k
14 votes

Where is the extended Hückel method (EHM) still used today?

I know of at least one place, where it is relatively common to use the extended Hückel theory in practise: in generating initial guess orbitals for further electronic structure calculations. The most ...
Martin - マーチン's user avatar
11 votes

State of the art in computational materials design

I am sure there are A LOT of authors publishing papers to answer this very question. Mainly because the theories employed have face a paradigm since "one-size-doesn't-fit-all". Here are the ...
gogo's user avatar
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10 votes
Accepted

Compute polarizability after each step of relaxed scan in Gaussian 16

This python script will read the logfile from the scan and generate the corresponding gaussian input files. ...
Hemanth Haridas's user avatar
9 votes
Accepted

Is it possible to get complex numbers as solutions for a secular determinant in simple Hückel method (SHM)?

In the Huckel method, you are just generating a very simplified version of the molecular Hamiltonian and determining it's eigenvalues. The molecular Hamiltonian will always be a Hermitian matrix (for ...
Tyberius's user avatar
  • 15.5k
8 votes

Semi-empirical software for bands calculations

DFTB+ One option is DFTB+. It is free, open source, has been around for more than a couple years now, and has a fairly big community. You are also very lucky, since your question is about the band ...
Nike Dattani - No Free Time's user avatar
7 votes

Symmetry-preserving low-level structural relaxation

ASE has a FixSymmetry constraint that preserves spacegroup symmetries. It works with a variety of structure optimization algorithms. You could use LAMMPS as the engine or one of the many other ...
wcw's user avatar
  • 1,893
6 votes

MOPAC: Is there a simple way to display geometry trajectories

I created a Python script to manipulate the MOPAC output, saving a XYZ file with all the structures from the optimization step. Then, the XYZ can be loaded into Jmol software and do the animation. The ...
Camps's user avatar
  • 23.4k
6 votes

SCF not converging during RHF/STO-3G geometry optimisation

Based on your input file, I tried to run the calculation in my machine. As you didn't specified how did you obtain the original structure (assembled by hand or downloaded from structure database), I ...
ksousa's user avatar
  • 4,108
5 votes

SCF not converging during RHF/STO-3G geometry optimisation

If you look at your last five iterations, you will see that the density change (which is what matters most for SCF convergence) is getting smaller in each iteration, meaning that the calculation is ...
Nike Dattani - No Free Time's user avatar
5 votes
Accepted

Symmetry-preserving low-level structural relaxation

GULP GULP (General Utility Lattice Program) uses specific forcefields for different type of systems and it is designed to work with periodic conditions. Also, it has defined several type of potential ...
Camps's user avatar
  • 23.4k
3 votes

Scripts to extract data from MOPAC calculations?

I created the script bellow to extract the data I'm interested in from all MOPAC out files put inside a given folder and create a CSV file with all the data: ...
Camps's user avatar
  • 23.4k
2 votes

How can I calculate ionization energies and electron affinities with MOPAC?

The simple answer is that the heat of formation difference between two charge states is the most conceptually and practically accurate way to estimate an ionization potential (IP) or electron affinity ...
Jonathan Moussa's user avatar

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