[gmx-developers] Verlet-Tables integration

[David van der Spoel]

Den 2018-11-13 kl. 23:53, skrev Mark Abraham:
> Hi,
> 
> Not much has happened. I did some basic cleanup, and Erik has worked on 
> some table classes in src/gromacs/tables. Alfredo has some old GPU 
> kernels buried somewhere on Gerrit.
At one stage we had a number of competing table implementations in 
gerrit, Berk and I worked on this one 
https://gerrit.gromacs.org/#/c/4734/ but it seemed somehow it was 
superseded by Erik's version. Then I lost track.
> 
> It would be good to identify a use case that someone has interest in to 
> e.g. contribute coding time, test cases, design idea sounding board. 
> AFAIK none of the GROMACS core developers uses this feature, so their 
> priorities tend to align elsewhere. However, we know it's useful to 
> people, so we'd like to find a group that can work together to make it 
> happen!

Here's a use case, Gaussian potential functions, that we use gromacs 
4.6.7 for:
https://pubs.acs.org/doi/10.1021/acs.jctc.8b00507

Gaussian we can still implement analytically, but for Slaters that is 
not going to be very efficient, so we need to generate tables inside mdrun.

> 
> Some of those dot points are a bit out of date, but the general list of 
> things to do is about right.
> 
> Mark
> 
> On Tue, Nov 13, 2018 at 3:48 PM Adriaan Riet <adriaan.riet at case.edu 
> <mailto:adriaan.riet at case.edu>> wrote:
> 
>     Hello everyone,
> 
>     I know that Feature #1347 talks about the necessary steps to get
>     tables into Verlet (pasted below). I'm curious to know where this
>     sits. I'm happy to contribute where (if) I can, but don't see
>     clearly where to jump in. Have the points of the list been
>     integrated into redmine feature requests? Have any of these been
>     implemented yet?
> 
>     Thanks,
>     Adriaan Riet
> 
>     Things to do (roughly in order):
> 
>       * support regressiontests being able to read tables from grompp or
>         mdrun, so that new functionality in the code doesn't need
>         matching changes to the other repo for valid testing in the few
>         cases where they use tables (|*CSTab*| in group-scheme kernels)
>       * add integration tests, e.g. a Martini-style(?) non-bonded, and
>         several kinds of bonded interactions
>       * extract code from mdlib (particularly init_forcerec) so that it
>         is callable at grompp time, make sure grompp can issue all notes
>         and warnings, permit mdrun to repeat any of those that it might
>         need to. Keep code for making hardware-specific layout decisions
>         in mdrun, because we won't know whether the kernels need tables
>         for CPUs or GPUs until then. If we can do it without significant
>         loss of accuracy, grompp should handle any regularization of the
>         user input (e.g. by constructing and testing CPU and GPU tables,
>         if necessary).
>       * move e.g. dihedral-interaction table reading to grompp, bump
>         .tpr version, write to .tpr, read in mdrun, add infrastructure
>         to support gmx check and gmx dump on new .tpr contents
>       * move angle- and bond-interaction table reading to grompp,
>         probably another .tpr version bump
>       * move short-range interaction tables to grompp for group scheme
>       * extend |[pairs]| to permit atom-type pairs to use an interaction
>         shape read from a table, e.g. from a file named on that line of
>         the topology. Should we have a per-pair-type scaling parameter?
>         Requirements for simulations that use only user tables, and
>         those that mix user tables with normal short-ranged interaction
>         types probably differ.
>       * add Verlet-scheme table-support infrastructure
>       * add CPU kernels (hopefully in new scheme)
>       * add GPU kernels (recycle from Alfredo's patch in gerrit)
>       * after some time passes and master branch rebases enough, remove
>         workaround from regressiontests (which is anyway only needed for
>         group-scheme kernel testing)
> 
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> 


-- 
David van der Spoel, Ph.D., Professor of Biology
Head of Department, Cell & Molecular Biology, Uppsala University.
Box 596, SE-75124 Uppsala, Sweden. Phone: +46184714205.
http://www.icm.uu.se