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update RTP/EMD docs (#4990)

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André Nyberg Borrfors 2026-03-23 16:44:07 +01:00 • committed by GitHub
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docs/methods/sampling/ehrenfest.md
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@ -249,7 +249,6 @@ RTP.inp is the input file used for such simulation:
FILENAME =applied_field
&END FIELD
&PROJECTION_MO
REFERENCE_TYPE SCF
REF_MO_FILE_NAME RTP-RESTART.wfn
REF_MO_INDEX -1
SUM_ON_ALL_REF .FALSE.
@ -262,7 +261,6 @@ RTP.inp is the input file used for such simulation:
&END PRINT
&END PROJECTION_MO
&PROJECTION_MO
REFERENCE_TYPE XAS_TDP
REF_MO_FILE_NAME ${EXC_STATE_1}
TD_MO_INDEX -1
SUM_ON_ALL_TD .FALSE.
@ -273,7 +271,6 @@ RTP.inp is the input file used for such simulation:
&END PRINT
&END PROJECTION_MO
&PROJECTION_MO
REFERENCE_TYPE XAS_TDP
REF_MO_FILE_NAME ${EXC_STATE_2}
TD_MO_INDEX -1
SUM_ON_ALL_TD .FALSE.
@ -387,18 +384,18 @@ Note that the smaller this threshold, the more iterations per time step will be
Hence, we have set the maximal iteration number
[MAX_ITER](#CP2K_INPUT.FORCE_EVAL.DFT.REAL_TIME_PROPAGATION.MAX_ITER) at quite high value of 100.
The time step used is rather small since we have to describe a core-hole excitation process that
takes place with a typical frequency of 529 eV. Following the rule of thumb to set the time step to
about 10 times the field frequency, we set [TIMESTEP](#CP2K_INPUT.MOTION.MD.TIMESTEP) to
takes place with a typical frequency of 529 eV. Following the rule of thumb to use a time step 10
times smaller than the field wavelength, we set [TIMESTEP](#CP2K_INPUT.MOTION.MD.TIMESTEP) to
`[fs] 0.00078`
### Field parameters
The field is defined by its envelope, its intensity, its polarization along the laboratory x, y, and
z-axis, its wavelength, and the original phase. Several types of field envelopes can be used. Here
we use a Gaussian one with a width of $\sigma=0.3073$ fs and centered at $T0=1.3190$ fs. The
intensity used is 4.08E+13 W.cm$^{-2}$. Along with a carrying frequency of 529 eV (approximately
2.34374655955 nm), it should promote about $10^{-3}$ from the Oxygen 1s to the first available
excited state.
we use a Gaussian with a width of $\sigma=0.3073$ fs and centered at $T0=1.3190$ fs. The intensity
used is 4.08E+13 W.cm$^{-2}$. Along with a carrying frequency of 529 eV (approximately 2.34374655955
nm), it should promote about $10^{-3}$ electrons from the Oxygen 1s to the first available excited
state.
```none
&EFIELD
@ -429,7 +426,6 @@ First, let us have a look at the projection toward the ground state:
```none
&PROJECTION_MO
REFERENCE_TYPE SCF
REF_MO_FILE_NAME RTP-RESTART.wfn
REF_MO_INDEX -1
SUM_ON_ALL_REF .FALSE.
@ -450,10 +446,10 @@ All the time-dependent Molecular Orbitals are projected by setting
to `.FALSE.`.
This calculation is spin-independent so one does not have to define the spin of the MO to project.
The reference to projected to is loaded from the file `RTP-RESTART.wfn`, which is the ground state
obtained after the SCF cycles. Note that you can define a wave-function that is not the ground state
as long as the wave-function description (basis set, number of electrons...) is the same as the one
used for the real-time propagation. The `REFERENCE_TYPE` defaults to `SCF`.
The reference to project onto is loaded from the file `RTP-RESTART.wfn`, which is the ground state
obtained from the SCF calculation. Note that you can define a wave-function that is not the ground
state as long as the wave-function description (basis set, number of electrons...) is the same as
the one used for the real-time propagation.
All the molecular orbitals available in this reference wave-function will be used as a reference for
the projection by setting
@ -476,7 +472,6 @@ excited-states:
```none
&PROJECTION_MO
REFERENCE_TYPE XAS_TDP
REF_MO_FILE_NAME ${EXC_STATE_1}
TD_MO_INDEX -1
SUM_ON_ALL_TD .FALSE.
@ -489,12 +484,17 @@ excited-states:
```
In this case, all the time-dependent MO are involved in the projection and stored separately. This
time, the reference wave function is supposed to be from an XAS_TDP calculation, see Linear Response
input file in the
[tutorial archive](https://github.com/cp2k/cp2k-examples/tree/master/rtp_field_xas). Running with
the proper parameters, this XAS_TDP run saves one .wfn file per excited state. Using
`REFERENCE_TYPE XAS_TDP`, the projection uses automatically the state saved in the produced wave
function file as the reference:
time, the reference wave function is obtained from an XAS_TDP calculation, see the
[RESTART_WFN](https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XAS_TDP/PRINT/RESTART_WFN.html)
option of the XAS_TDP module in the CP2K input reference. When requesting to print an excited state
wavefunction, the resulting .wfn file is that of the groundstate wavefunction except that the
initial orbital from which the electron is excited is replaced by the final orbital where the
electron is excited to. Therefore, please be aware that the ordering of the orbitals will affect
which file the excited orbital is written to. This is especially important to look out for if the
initial orbital is not of the lowest energy.
XAS_TDP will save one .wfn file per printed excited state, and the projection during RTP is obtained
by:
$$
n_{\omega}^i(t) = |<\omega | \psi_i(t)>|^2 = |\sum_{ab} \left( C_\omega^a \right)^* c_i^b(t) S_{ab} |^2