Matter Modeling Asked on November 24, 2021
If you do a bibliography search about the codes used in matter modeling, you will find a large list.
I played with a few of them (both free and commercial) and one of my findings is that the properties they can calculate are different, even being important properties. I am aware that they used different basis set (numerical orbitals, Slater functions, Gaussian function, Plane waves), considered all the electrons or just valence electrons, used different types of pseudopotentials, etc.
My doubt is about the different properties they can calculate.
Is this difference only related to the developers choice or there are some properties that can only be calculated following a given set-up?
(for a given set-up I mean, a given type of basis-set or an specific pseudopotential type, for example)
Only a partial answer: some setups are surely better suited than others for a given property. Some developers recognize this and thus do not bother implementing properties for which their setup will be bad, other developers simply lack the time.
One example that I am familiar with are NMR/ESR properties. The ADF package (using Slater basis functions) can calculate some such properties, for which the performance is thought of as better than with Gaussian basis functions. In the latter case, one attempts to handle the problem of the missing cusp at the nucleus by decontracting the basis set (meaning that the number of primitives is equal to the number of AO), and possibly even adding more "core" functions.
Answered by TAR86 on November 24, 2021
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