[CP2K:2851] Calculation of Exact exchange potential

Juerg Hutter hut... at pci.uzh.ch
Fri Sep 17 14:14:39 UTC 2010

Dear Andrey

> Dear CP2K developers,
> 1.  I would like to calculate the exact exchange potential.
> Are there any routines for the orbital derivatives calculation?

I assume you want to calculate the OEP ?
The orbital derivatives in the code relate to specific energy terms
and they will (most likely) not be of use to you.
In my opinion you have to use the HFX code.

> 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?

Are you refering to the term dpsi_i/drho ? This is not available.

> 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?

dbcsr is the general sparse matrix format (Distributed Blocked Compressed 
Sparse Row). It is used for all matrices (except the orbitlas, but this 
might change soon).

fm stands for full matrix (all elements are stored). The fm matrices are
also distributed according to BLACS. The fm form is needed to make use
of the ScaLapack routines. To diagonalize the Kohn-Sham matrix, for 
example, you first have to convert the dbcsr format to fm format and then
call the ScaLapack routine.



> Thanks,
> Andrey Laktionov
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