Primitive integrals/contraction coefficients

[maxscheurer]

Primitive integrals/contraction coefficients

[sunqm]

1. Overlap is defined as the product of two Gaussians. You should compare to

ref = integrate(
    exp(-2.0 * (x ** 2 + y ** 2 + z ** 2)) ** 2, (x, -oo, oo), (y, -oo, oo), (z, -oo, oo)
)

2. for s-type orbitals, int1e_ovlp includes the normalization factor for angular part 1/4pi

[maxscheurer]

Thanks, the 1/(4pi) did the trick 👍 Regarding 1., I already had a product of two Gaussians, note the ** 2 after the exp function.
I'll leave this issue open for follow-up questions during my implementation if that's okay.