IP as CV and much much ... much more

[Peter]

Thank you Teo! :)

Regards,
Peter

On Feb 12, 6:47 pm, Teodoro Laino <teodor... at gmail.com> wrote:
> Dear All,
>
> as a follow-up on the request of Peter of using the ionization potential as CV, I decided to implement this feature together with an infinite amount of other feasible combination.
> The trick is in using the MIXED force_eval: you can specify one force_eval for a neutral specie and another for the same specie with a -1 charge, and use the difference between the two energies as a CV (it is implemented again the possibility to specify whatever functions of the energy).
>
> There are many other possibilities one can do:
> -) use different subsystems
> -) use different Hamiltonians
> -) use excited states and differences between excited states to explore conical intersections (when these will be available in cp2k!.. so not yet at the moment)
>
> Again.. as usual.. the only limit is your imagination. I hope you all enjoy this little programming effort.
> For any question/request, do not hesitate to contact me.
>
> Regards to all,
> Teo
>
> -------
>
> As an example, the IP CV can be defined in the following way (tests/QS/regtest-meta/H2O-meta-IP.inp) :
>
> #These computes the energies for the two systems
> @SET CHARGE  0
> @SET LSD 0
> @include dft_force_env.inc
> @SET CHARGE -1
> @SET LSD 1
> @include dft_force_env.inc
>
> #this force_eval combines for the evolution of the EOM
> &FORCE_EVAL
>   METHOD MIXED
>   &MIXED
>     MIXING_TYPE GENMIX
>     NGROUPS  2
>     &GENERIC
>       MIXING_FUNCTION E1+k*E2
>       VARIABLES E1 E2
> # Propagate the Equation of Motion according to the neutral state Hamiltonian by using only the energy of the charge == 0 system
>       PARAMETERS k
>       VALUES 0.
>     &END
>   &END
>   &SUBSYS
>     &CELL
>       ABC 5.0 5.0 5.0
>     &END CELL
>     &COORD
>       O   0.000000    0.000000   -0.065587
>       H   0.000000   -0.757136    0.520545
>       H   0.000000    0.757136    0.520545
>     &END COORD
>     &KIND H
>       BASIS_SET DZVP-GTH-PADE
>       POTENTIAL GTH-PADE-q1
>     &END KIND
>     &KIND O
>       BASIS_SET DZVP-GTH-PADE
>       POTENTIAL GTH-PADE-q6
>     &END KIND
>     &COLVAR
>        &U
>          &MIXED
> # we define the difference of the two energies as CV.
> # You can specify here in general whatever function you like!!!!!
>            ENERGY_FUNCTION E2-E1
>            VARIABLES E1 E2
>          &END
>        &END
>     &END COLVAR
>   &END SUBSYS
> &END FORCE_EVAL