Suggestion: Time windows for calculation of regions of interest

[Paul Hockett]

[Apologies for the double posting, put this on GitHub before realising there was this list]

Currently time-steps (as I understand it) are defined in the input file from tstart to tend, in tn steps. This range must span the laser pulse duration. For regions of interested far from t0, e.g. 1/2 revival, this results in unnecessarily long calculations as all time-steps between t0 and tx must be calculated, and this becomes even worse if high temporal resolution results are sought.

A nice addition would therefore be a way to choose the time-window of the outputs independently of the TDSE time-window (i.e. independently of the laser pulse). This could be via an additional, optional set of inputs, e.g. {t1,t2,tn; t3,t4,tn;...}, where tx specify start and end times of interest, with tn steps between, and one could specify several different regions of interest.

Optionally, this could also replace the current tstart/tstop definition with the TDSE region instead being chosen automatically to match the input laser pulse parameters, depending on whether one wishes to retain transparent user control over this parameter or not.

[Jonathan Underwood]

Hello Paul,

On 20 May 2013 18:53, Paul Hockett <phoc...@gmail.com> wrote:
> [Apologies for the double posting, put this on GitHub before realising there
> was this list]
>

It's definitely a good thing that you put the feature request on
github so we can keep track of them.

> Currently time-steps (as I understand it) are defined in the input file from
> tstart to tend, in tn steps. This range must span the laser pulse duration.
> For regions of interested far from t0, e.g. 1/2 revival, this results in
> unnecessarily long calculations as all time-steps between t0 and tx must be
> calculated, and this becomes even worse if high temporal resolution results
> are sought.
>
> A nice addition would therefore be a way to choose the time-window of the
> outputs independently of the TDSE time-window (i.e. independently of the
> laser pulse). This could be via an additional, optional set of inputs, e.g.
> {t1,t2,tn; t3,t4,tn;...}, where tx specify start and end times of interest,
> with tn steps between, and one could specify several different regions of
> interest.
>

Yep, after we spoke I started hacking on some changes for this, so
it's underway.

> Optionally, this could also replace the current tstart/tstop definition with
> the TDSE region instead being chosen automatically to match the input laser
> pulse parameters, depending on whether one wishes to retain transparent user
> control over this parameter or not.

At the moment I am leaning towards staying with manually specifying
the TDSE propogation stat and end points. It may be possible to work
these out sensibly from the laser parameters, but for now I am working
on the principles of least surprise, and garbage in garbage out. It's
definitely worth revisiting this down the line though.

J.

[Paul Hockett]

On balance I think I agree with the full control being kept in - I didn't really consider it before, but for multiple laser pulses it makes a lot of sense to be able to define transparently all the required time-windows, and maintain independent control over the TDSE and free propagation regions.  Christer's code was designed for one or two Gaussian pulses only, so could always define a sensible integration region based on this (see, for example, lines 147 - 161 in his ffa_sym.cpp).