Questions tagged [semi-empirical-method]

For questions about methods (typically in electronic structure theory) that use experimental parameters as part of their formulation

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MOPAC: Is there a simple way to display geometry trajectories

I would like to display MOPAC geometry trajectories for structure minimization and transition state searching. Is there a simple way to achieve that ? Avogadro can display only final geometry from ...
Miro Iliaš's user avatar
2 votes
1 answer

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

can I simply calculate the ionization energy (IE) as the difference between the neutral and the charged system Heat of formation (Hf) with MOPAC ? The same question is with the electron affinity (EA). ...
Miro Iliaš's user avatar
6 votes
1 answer

Compute polarizability after each step of relaxed scan in Gaussian 16

I am computing a relaxed 2D scan with Gaussian 16 in order to reproduce some computational data. I am interested in computing the dipole moment vector and the (static) polarizability matrix after each ...
capitn96's user avatar
7 votes
1 answer

Scripts to extract data from MOPAC calculations?

I am doing calculations with MOPAC semi-empirical package. As I have many systems (around 40), extracting the date manually, besides being tiring it can cause errors. I already worked with ASE, but ...
Camps's user avatar
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6 votes
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SCF not converging during RHF/STO-3G geometry optimisation

I'm new in the field of QM methods and I've run into a problem for which I can't find a solution online. I have tried with different basis sets, I've raised the maximum number of iterations and number ...
user avatar
6 votes
2 answers

Symmetry-preserving low-level structural relaxation

I would like some suggestions on how to do structural relaxation (while I'm at it, let me list some synonyms for search exposure - geometry optimization, structural refinement, energy minimization etc)...
David CY's user avatar
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7 votes
1 answer

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

Past semester we revisited the Hückel molecular orbital theory at class. One day I was trying to solve some problems with SymPy, a Python module that is a computer algebra system (CAS), and noticed ...
ksousa's user avatar
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19 votes
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State of the art in computational materials design

With the advent of more computational power than ever in the recent years, interest in in silico design of interesting compounds has grown as well. I am wondering about the state of the art for the ...
Michael F. Herbst's user avatar
13 votes
1 answer

Semi-empirical software for bands calculations

In Semiconductor Physics, one of the main parameters of interest is the band gap. It is known that, in DFT, there are functionals that underestimate it. I came across the MOPAC program, a semi-...
Camps's user avatar
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27 votes
3 answers

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

The extended Hückel method (EHM) proved to be very useful through time, but there are better and affordable models today. One interesting thing about the model is the independence of the Hamiltonian ...
schneiderfelipe's user avatar