How to find the radial shells?

Questions
#1

I am revisiting some grid-related questions that are related to my concerns, and had a follow-up question based on this post.

Where does the number of radial shells come from for the SG-1 grid? The original paper does not seem to specify it, and I couldn’t find it mentioned explicitly elsewhere.

You also mentioned that “SG-1 it’s a bit tricky (requires you to compute the radial quadrature values)” - could you clarify how to compute the radial quadrature values in Q-CHEM?

image
image1800×1304 218 KB

#2

For the radial points, SG-2 and SG-3 use a “double exponential” (also known as tanh) quadrature, as described in the original paper:
https://doi.org/10.1002/jcc.24761
The radial quadrature weights are pre-computed, they are not computed in Q-Chem. For SG-1, it is a pruned Euler-Maclaurin-Lebedev grid, see
https://doi.org/10.1016/0009-2614(93)80125-9