There seems to be something wrong in the cartesian version:

mol = gto.M(atom="He 0 0 0; Ne 0 0 2.0", basis="def2-qzvp", unit="Bohr", spin=0, cart=True)
gives
EXC (ref) = -1.35529407216016e+01
EXC (calc) = -1.33526784882510e+01
EXC Diff = -1.47762937552981e-02
| VXC (ref) |_F = 2.47705806355824e+01
| VXC (calc) |_F = 1.81479250598974e+01
RMS VXC Diff = 9.16350291581032e-02

mol = gto.M(atom="He 0 0 0; Ne 0 0 2.0", basis="def2-qzvp", unit="Bohr", spin=0, cart=False)
gives
EXC (ref) = -1.35529277410941e+01
EXC (calc) = -1.35529447345960e+01
EXC Diff = -1.25386206588653e-06
| VXC (ref) |_F = 1.65203073321537e+01
| VXC (calc) |_F = 1.65202505202321e+01
RMS VXC Diff = 1.28538169430761e-04

I have tried the use of cmake without installing gauxc first via the installation instructions and see how far cmake gets. I suppose this is how other programs aim to integrate skala via gauxc.

I encountered some problems:

1. (Mac specific) The standard apple compiler is a modified clang compiler where they explicitly switched off openmp support. There are different solutions for this specific case:
   • Switch the OpenMP to OFF in the CMakeLists.txt
   • Specify a different compiler via the CXX environment variable or overrule the C++ compiler while invoking cmake via -DCMAKE_CXX_COMPILER=
2. Torch could not be build
   I am still looking for a solution

1. (Mac specific) The standard apple compiler is a modified clang compiler where they explicitly switched off openmp support

This is a good point, I will add it to the troubleshooting

2. Torch could not be build

That's a required dependency for us and I see no realistic way to build libtorch reliably on a user machine. I will also add this into the troubleshooting to highlight that it is important to provide libtorch and that it cannot be built on the fly like other dependencies.