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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1 answer
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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
159 views

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
2 answers
435 views

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
248 views

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
251 views

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
2 answers
285 views

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
187 views

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
643 views

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