[gmx-users] energy terms in following runs

Anton Feenstra feenstra at chem.vu.nl
Mon Feb 24 08:16:48 CET 2003


David van der Spoel wrote:
> On Fri, 2003-02-21 at 14:52, Ester Chiessi wrote:
[..]
>>
>>Pheraps this happened because I changed the time step?
[...]
> If you change the time step the kinetic energy will be discontinuous.

Worse: your velocities will be wrong; they are from the 'half' timestep
in the Leapfrog algorithm, but if you change timestep, the 'location'
of the half timestep will have shifted... It should be possible to
correct for that, perhaps by taking an appropriately weighted average
between velocities at last step and one-but-last, but usually you
do not write .trr every md step.


-- 
Groetjes,

Anton
  _____________ _______________________________________________________
|             |                                                       |
|  _   _  ___,| K. Anton Feenstra                                     |
| / \ / \'| | | Dept. of Pharmacochem. - Vrije Universiteit Amsterdam |
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| \_/ \_/ | | | Tel: +31 20 44 47608 - Fax: +31 20 44 47610           |
|             | Feenstra at chem.vu.nl - www.chem.vu.nl/~feenstra/       |
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