Interfacing

General hints

The first is that the density matrix has to be scaled by half before calling the routine, and that is already counting that D is spin-restricted. Similarly, the output F needs to be multiplied times two. This is probably historically related to how DALTON handles data.

The AO primitive weights are expected to contain the spherical harmonic normalization constant. This is essential because there are different ways of absorbing the angular and radial normalizations into different quantities, depending on definitions.

Where can I find examples?

• https://github.com/dftlibs/xcint/blob/master/test/energy_spherical.cpp
• https://github.com/dftlibs/xcint/blob/master/test/test.f90

Where is the interface?

The Python interface is currently broken but the Fortran and C interfaces work.

Yes, we need some documentation here but hopefully these files are a good start:

• https://github.com/dftlibs/xcint/blob/master/api/xcint.h
• https://github.com/dftlibs/xcint/blob/master/api/xcint.f90