Calculation of Exact exchange potential

[Andrey]

Dear CP2K developers,

1.  I would like to calculate the exact exchange potential.
 Are there any routines for the orbital derivatives calculation?

 I found the following routines dealing with orbital derivatives.
sic_explicit_orbitals, qs_ks_s2_restraint, low_spin_roks.
All of them use the xc_vxc_pw_ctreate1 method.
 Is it possible to use them for foregoing purposes?
See  Line 1813: xc_vxc_pw_ctreate1(...)  in qs_ks_methods.F
As I understand xc_vxc_pw_ctreate1 imply Fourier transform of
gaussians, so it should be relatively expensive.

2. Does the routine for taking the orbital derivative with respect to
the density exist?

3. What is the difference between dbcsr and fm types.
For example, I found two subroutines: copy_dbcsr_to_fm and
copy_fm_to_dbcsr.
What is the their purposes? What is the differences?

Thanks,
Andrey Laktionov