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QTAIM: a package for quantum theory of atoms in molecules

Posted 11 months ago
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Hello All,

(I have set Independence Day (Observed) as my pencils-down moment to publicize a Wolfram Language/Mathematica package for performing computations and visualizing results from Quantum Theory of Atoms In Molecules (QTAIM) calculations on electronic structure theory wave functions.

QTAIM endeavors the answer the question, "Are there discernable atoms inside of molecules?" The answer according to Bader and co-workers is yes, if you define an atom as the basin/union of all steepest ascent paths and a nucleus, which is the attractor. Since there is zero-flux between these regions, they are proper quantum subsystems, just like the molecule/crystal is.

Here is the water molecule (H2O) in this representation:

Atomic Basins

What motivated me to get going on creating a package was the new SliceVectorPlot3D routines, which make plotting these quantities a dream:

Gradient Field on Planes of Symmetr

The code is hosted here:

which has this code and more extensive discussion.

Wolfram Language/Mathematica is great for this. Great algorithms like ABM differential equation solver, and excellent graphics for 2D/3D fields. I t features several ways to get data in, so it can be file-based or scripted from PySCF.

Well, I should keep it brief, and I look forward to any comments you have.

Best regards, Eric

An overview of the methods and results can be found here: