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7 votes

Quantifying relativistic effects in DFT calculations

In reality, the contribution to an energy due to relativity, would be the difference between the "exact" energy with a model that captures all relativistic effects, versus a model that ...
Nike Dattani - No Free Time's user avatar
6 votes
Accepted

What would be the criteria for comparing basis set?

"What would be the criteria for comparing similar basis set?" Gaussian basis sets are usually characterized by the numerical values of the exponents and the contraction coefficients. If ...
Nike Dattani - No Free Time's user avatar
6 votes

DFT calculation for conjugated polymers

Apologies I do not have enough reputation points to post this as a comment. You might have already considered other electronic structure methods, but I would like to suggest consider using density ...
squareroottwo's user avatar
6 votes
Accepted

Kill or let be: Is this calculation stuck or just very slow?

"I don't know if the calculation is just stuck and wasting compute resources, or if it is actually still working." When that happens, I log into the compute node and run the ...
Nike Dattani - No Free Time's user avatar
4 votes

Explicit form of Hartree Fock analytic gradient with contracted GTOs? With or without density fitting

Molecular Electronic-Structure Theory, by Helgaker et al., is an extremely comprehensive textbook reference for electronic structure on finite systems. I take the following from Section 10.8.3 (pp. ...
elutionary's user avatar
4 votes

How to remove f functions from a cc-pVQZ basis set in CFOUR format?

If you use the Basis Set Exchange anyway, I recommend you have a look at the Python library which makes it quite simple to modify basis sets in any way you want. The code below does what you want but ...
Susi Lehtola's user avatar
  • 19.7k
3 votes
Accepted

How to remove f functions from a cc-pVQZ basis set in CFOUR format?

The CFOUR basis format is laid out on their website, but it might be in a little more detail and a little more abstract than you need, so I'll walk through your example of Boron cc-pVQZ to make it ...
Tyberius's user avatar
  • 15.5k
2 votes

Numerical atomic orbitals vs Gaussian-type orbitals for molecular calculations

In some cases at least, NAO give smaller BSSE (basis set superposition error). Here is the figure from the FHI-aims paper: The BSSE here is the difference between red and black lines. It is small, ...
user36313's user avatar
  • 730
1 vote
Accepted

Computing energy and forces directly from machine learned wavefuntion/density

You can't do Hartree-Fock with densities, only. You need density matrices to evaluate exact exchange. However, you can do semilocal density functional calculations with knowledge of the electron ...
Susi Lehtola's user avatar
  • 19.7k
1 vote
Accepted

How to exploit STO-nG coefficients from basissetexchange (BSE)?

My first question is: why write your own package if you already have many open source ones upon which to build? NWChem, psi4, pyscf, … Note: Ne does not have d-functions within STO-6G. For the d-...
MSwart's user avatar
  • 1,064

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