How to generate Alchemy dataset?

[anny0316]

Hello, great work.
now, I want to convert SMILES to 3D Cartesian coordinates. By reading Alchemy paper I got the following ideas. The idea is to complete the conversion of SMILES to 3D coordinates in 3 steps:

We first used RDkit to parse SMILES string and built the Cartesian coordinates with MMFF94 force field optimization.
The second pass employed the HF/STO3G theory (incorporate quantum mechanical effects) to generate a preliminary geometry.
In the final pass of geometry relaxation, we used the B3LYP/6-31G(2df,p) model with the density fitting approximation for electron repulsion integrals.
I have finished the first step, can you give me some advice about the second and the third steps? Thanks a lot.