[CP2K:2871] real time propagation under DDAPC charge constraint

Hanning Chen chenh... at gmail.com
Mon Oct 4 18:08:38 CEST 2010


Dear Juerg,

  I agree with you that it is not trivial to find a perfect charge
constraint strategy. But, I have a feeling that the RT-TDDFT should work
under DDAPC constraint. According to the constrained DFT formalism,

                                      (H0  + Vc * Wc ) * Phi = E * Phi

where Phi is the wavefunction, Vc is the constrain Hartree potential and Wc
is the constrain operator. After checking the "cp_ddapc.F" file, the Vc
seems to be given in variable "v_hartree_gspace", my question is how to
obtain the constrained operator Wc ?

  Once we know both Vc and Wc, we should be able to get the "constrained
Hamiltonian", under which the wavefunction only has a stationary phase shift
upon time evolution, becasue Phi is now the eigenstate of ( H0 + Vc * Wc). I
believe It is a rigorous way to check whether the constrained wavefunction
is well converged.

  Thanks.

Hanning



On Mon, Oct 4, 2010 at 9:18 AM, <hut... at pci.uzh.ch> wrote:

> Hi
>
> the DDAPC code was not indended/tested to work with RT-TDDFT.
> However, we think the DDAPC restraint might work as is, for the
> DDAPC constraint we have serious doubts that it is correct.
>
> regards
>
> Juerg
>
> -----cp... at googlegroups.com wrote: -----
>
> To: cp... at googlegroups.com
> From: Hanning Chen <chenh... at gmail.com>
> Sent by: cp... at googlegroups.com
> Date: 10/02/2010 07:29PM
> Subject: [CP2K:2868] real time propagation under DDAPC charge constraint
>
> Dear CP2K developers,
>
>   I am trying to run a real-time propagation under DDAPC charge
> constraint. It seems to me that the following lines of codes in
> "qs_ks_methods.F" are still executed, and thus update the
> ks_env%v_hartree_rspace to apply the constraint. Am I right ?
>
>   Thanks.
>
> Hanning
>
>
> "qs_ks_methods.F"
>
>       ! In case decouple periodic images and/or
> apply restraints to charges
>        IF (do_ddapc) THEN
>           CALL
> qs_ks_ddapc(qs_env, auxbas_pw_pool, rho_tot_gspace, v_hartree_gspace,&
>
>               
> v_spin_ddapc_rest_r, energy, calculate_forces, ks_env,
> ks_matrix,    &
>               
> just_energy, ddapc_restraint_is_spin, explicit_potential, error)
>        ELSE
>          
> explicit_potential      = .FALSE.
>
>          
> ddapc_restraint_is_spin = .FALSE.
>           IF (.NOT.
> just_energy) THEN
>             
> CALL pw_transfer(v_hartree_gspace%pw, ks_env%v_hartree_rspace%pw,
> error=error)
>             
> CALL pw_scale(ks_env%v_hartree_rspace%pw,
> ks_env%v_hartree_rspace%pw%pw_grid%dvol,&
>
>                  
> error=error)
>           END IF
>        END IF
>
>
>
>
>
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