[gmx-users] Number of simulated annealing points

Tim Moore tcmoore3 at gmail.com
Wed Mar 30 20:34:48 CEST 2016


I'm currently simulating bilayer systems, where our equilibration scheme
involves randomly adjusting the temperature to values within a given range.
The temperatures can be predetermined, so the we can use the simulated
annealing module within GROMACS. However, the maximum number of allowed
temperatures in simulated annealing is 254 points, meaning we can only use
254 points before the cycle starts over (using periodic annealing). I need
many more set points than that, so this is a problem. I see in the source
code there is a parameter MAXPTR = 254 that defines the maximum number of
elements allowed. This brings me to my question: is there any reason to NOT
change this to a larger number to accommodate the larger number of
temperature points I need? I see two easy workarounds, the first being to
increase MAXPTR; the second being make a new parameter MAXPTR2 and use that
only for the str_nelem() calls associated with the annealing. Is either of
these preferred over the other, or is there a better solution? Also, what
is the motivation for setting MAXPTR = 254 - is it some sort of
optimization? Will setting MAXPTR to a higher value hurt performance?


Tim Moore

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