Lionel

> `m_kern_exx_eri` and `m_kern_exx_dummy` are also very similar with the main difference being that arrays are allocated at the beginning of `m_kern_exx_dummy`. Therefore, this can also likely be refactored to...

> After comparing `m_kern_exx_eri` and `m_kern_exx_eri_gto`, the only differences seem to be that arrays are allocated in `m_kern_exx_eri` but not `m_kern_exx_eri_gto` and that `m_kern_exx_eri_gto` calls `compute_eri_hoh` at it's [deepest point](https://github.com/OrderN/CONQUEST-release/blob/f-exx-opt/src/exx_kernel_default.f90#L1878)...

> After comparing `m_kern_exx_cri` and `m_kern_exx_eri`, it does not look simple to reduce their duplication through refactoring. Many similar things are happening in both but the loop structures are different....

The bug arises from the use of FFTW in calculation of exact exchange. Bug reproduced with an old version of Conquest (prior Github creation). When switching to FFTE (Japanese implementation...

I think this is a good idea to provide examples for installation to new users (particulary students). There are pros and cons for providing system-specific full install recipies including libraries....