Skip to main content
15 votes
Accepted

What are the scientific justifications of the binding energy equation?

The justification is simple and comes from a very fundamental law of thermodynamics: Internal energy is a complete differential form and is independent of intermediate states and only depends on start ...
Mithridates the Great's user avatar
9 votes
Accepted

Is basis set superposition error reduced when using the GAPW method?

Short answer: no. The idea of the GAPW method described in Theor. Chem. Acc. 103, 124 (1999) is simply to speed up the evaluation of the Coulomb and exchange-correlation contributions. Quoting from ...
Susi Lehtola's user avatar
  • 19.7k
9 votes

What are the scientific justifications of the binding energy equation?

In general, a system composed of $K$ interacting subsystems have a potential energy at a specific configuration of its parts. For instance, a system of $M$ nuclei and $N$ electrons can be separated ...
Verktaj's user avatar
  • 2,731
6 votes
Accepted

Do the cc/pc/def2 basis sets mathematically converge to the CBS limit, assuming exact CI/DFT?

"Assuming exact CI/DFT, can the sequences of the results of an ever increasing cardinal number of the cc/pc/def2 basis sets mathematically shown to converge exactly to the CBS limit, according to ...
Nike Dattani - No Free Time's user avatar
3 votes

Does the accuracy of RI-MP2 follow the higher number of zetas of the main and fitting bases?

The term "basis set" literally comes from Fourier analysis in mathematics, and in Fourier analysis the "errors" systematically "cancel out", for example when integrating ...
Susi Lehtola's user avatar
  • 19.7k
2 votes

Can I freeze f functions from a TZ basis set during MP2 (but not during H-F) to speed up calculations?

The answer is no. Post-Hartree-Fock methods are famously slow to converge to the complete basis set limit due to their dependence on the unoccupied orbitals. Modern basis sets, such as the Dunning cc-...
Susi Lehtola's user avatar
  • 19.7k
2 votes
Accepted

Can I freeze f functions from a TZ basis set during MP2 (but not during H-F) to speed up calculations?

It depends on what you're intending to do: If you are comparing to benchmark results with this basis set, then likely no. If accuracy is very important to you, then likely no. If you are intending to ...
Nike Dattani - No Free Time's user avatar
2 votes

Do the cc/pc/def2 basis sets mathematically converge to the CBS limit, assuming exact CI/DFT?

To supplement Nike's answer, I would like to point out that the situation is even worse when you look at heavier atoms. While Gaussians do a pretty good job for the first periods of the periodic table,...
Susi Lehtola's user avatar
  • 19.7k
1 vote

Can I freeze f functions from a TZ basis set during MP2 (but not during H-F) to speed up calculations?

I'm not sure if freezing at the basis set level makes sense... However, you can make an MP2 calculation easier, by doing an active space approximation (freezing certain orbitals). You will need to ...
lex2763's user avatar
  • 391

Only top scored, non community-wiki answers of a minimum length are eligible