I recall seeing something online about how gromacs developers have
decided to focus on increasing the overall speed and allowing
generally large timesteps (via e.g. angle constraints) vs.
implementing multiple timestepping (no mailing list ref. sorry). I
agree that this is not a logically exclusive decision -- PME takes
>20% of the time so if they were doing it only 1/2 as often then
there is the possibility of a real speedup. Nevertheless, it would
need to be tested and perhaps the developers have indeed run these
tests -- I've simply not seen the results. One would think, though,
that PME could nearly always be done less often than, for example,
bonded interactions.
I agree with Erik that the work would be large, but I disagree that
the benefits would be small -- although I suspect that neither of us
has any data to support such claims :).
Unfortunately, the bottom line is that this is free software and if
you want it then you can code it. Or at the very least, you should
benchmark the benefits on NAMD and then submit an "enhancement"
bugzilla.
Chris.
-- original message --
The core developers have the answer for this one, but I can make an
educated guess:
Implementing it would mean a LOT of work and the rewards are small. The
latter because most particles will have rougly the same oscillation
period if one uses all-atom forcefields and turn on virtual sites and
constrains the bonds, hence the point of having multiple time steps is lost.
Vitaly Chaban skrev:
Chris,
An interesting question...
BTW, is there any philosophy of gromacs developers to avoid this
algorithm in the MD engine?
Vitaly
multiple timesteps are not possible as far as gromacs 4.0.7. NAMD
can do this.
-- original message --
Is it possible to carry out multiple time step molecular
dynamics simulations
in Gromacs
4.0. versions ? Could you
please give me some information about this issue ?
Thank you very much for your attention.
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