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 <div class="gmail_quote">On Mon, Oct 4, 2010 at 9:18 AM, <<a href="mailto:hut...@pci.uzh.ch">hut...@pci.uzh.ch</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> 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 -----<a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> wrote: ----- To: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> From: Hanning Chen <<a href="mailto:chenh...@gmail.com">chenh...@gmail.com</a>> Sent by: <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a> 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. <div class="im"> Hanning "qs_ks_methods.F" </div>      ! 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 -- You received this message because you are subscribed to the Google Groups "cp2k" group. To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>. To unsubscribe from this group, send email to <a href="mailto:cp2k%2Bun...@googlegroups.com">cp2k+uns...@googlegroups.com</a>. For more options, visit this group at <a href="http://groups.google.com/group/cp2k?hl=en" target="_blank">http://groups.google.com/group/cp2k?hl=en</a>. -- You received this message because you are subscribed to the Google Groups "cp2k" group. To post to this group, send email to <a href="mailto:cp...@googlegroups.com">cp...@googlegroups.com</a>. To unsubscribe from this group, send email to <a href="mailto:cp2k%2Bun...@googlegroups.com">cp2k+uns...@googlegroups.com</a>. For more options, visit this group at <a href="http://groups.google.com/group/cp2k?hl=en" target="_blank">http://groups.google.com/group/cp2k?hl=en</a>. </blockquote></div>