The dump position keyword

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Dump the atom positions (coordinates) to a text file named


dump_position interval <options>
  • The interval parameter is the output interval (number of steps) of the atom positions.
  • The <options> can be group or precision, which can be in any order.
  • The option group shoud have two parameters:
group grouping_method group_id

which means only dumping positions of atoms in group group_id within the grouping method grouping_method. If this option is not used, positions will be dumped for all the atoms.

  • The option precision shoud have one parameter which can only be single or double
precision single # output data with %0.9f format
precision double # output data with %0.17f format

If this option is not used, data will be output with the %g format.


Example 1

To dump all the positions every 1000 steps for a run, one can add

dump_position 1000

before the run keyword.

Example 2

Similar to the above example, but only for atoms in group 1 within grouping method 2

dump_position 1000 group 2 1

Example 3

Similar to the above example, but using double precision

dump_position 1000 group 2 1 precision double
# or equivalently:
dump_position 1000 precision double group 2 1


  • This keyword is not propagating. That is, its effect will not be passed from one run to the next.
  • The output file has an appending behavior and will result in a single file no matter how many times the simulation is run.

Output file