[CP2K:2872] real time propagation under DDAPC charge constraint

hut... at pci.uzh.ch hut... at pci.uzh.ch
Tue Oct 5 09:29:37 UTC 2010


Hi

as I said, we haven't looked into this. You are of course welcome to explore this further.
What I am concerned of is if the constraint is fulfilled during propagation.

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: 10/04/2010 06:08PM
Subject: Re: [CP2K:2872] real time propagation under DDAPC charge constraint

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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