Status and outlook

Status

The API is pre-alpha. Expect significant changes.

Grid generation

The grid generation has been moved outside XCint (the tests employ https://github.com/dftlibs/numgrid). This has the following advantages:

• Gives the caller the possibility to use other grid generators.
• Makes grid-based (MPI) parallelization relatively trivial.
• Moves grid-based (MPI) parallelization outside XCint.

MPI parallelization

MPI parallelization has been removed (see above section) as it can be introduced by the caller in very few lines. Not having MPI parallelization inside XCint simplifies the code and testing.

Functional parsing

This is currently done inside the code but should move outside. The reason why the functional is parsed and tracked inside the code is that XCFun does not allow to track the same functional using both the Fortan and C interfaces in the same run. Moving the functional parsing out now would break the Fortran interface of XCint.

Outlook

The plan is to also move the density evaluation (together with AO evaluation and “Fock”-type matrix distribution routines) outside of XCint to a separate library. This will make XCint very thin and compact. Another advantage is that this step will make XCint basis-set agnostic and point-group symmetry agnostic and therefore more general.