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dump_modify command

Syntax:

dump_modify dump-ID keyword value ... 

Examples:

dump_modify 1 format "%d %d %20.15g %g %g" scale yes
dump_modify myDump image yes scale no flush yes
dump_modify 1 header xyz 

Description:

Modify the parameters of a previously defined dump command. Not all parameters are relevant to all dump styles.

Each dump style has a default C-style format string which simply specifies %d for integers and %g for real values. The format keyword can be used to override the default with a new C-style format string. Do not include a trailing "\n" newline character in the format string.

The scale and image keywords apply only to dump atom commands. A scale value of yes means atom coords are written in normalized (scaled) units from 0.0 to 1.0 in each box dimension. A value of no means they are written in absolute distance units (e.g. Angstroms or sigma). If the image value is yes, 3 flags are appended to each atom's coords which are the absolute box image of the atom in each dimension. For example, an x image flag of -3 with a normalized coord of 0.5 means the atom is in the center of the box, but has passed thru the box boundary 3 times and is really 3 box lengths to the left of its current coordinate.

The header keyword determines the file format for the snapshots. A value of item means each keyword is prefaced by "ITEM:" which is compatible with previous versions of LAMMPS. A value of self is a self-documenting format where each keyword is followed by the number of rows and columns of data that follow it. This makes it easy to write post-processing codes that parse the dump output. A value of xyz writes the dump file in the XYZ format used by other molecular modeling codes. For dump atom commands, each line will have 4 quantities: the atom type and unscaled coordinates. For dump custom commands, each line will still list the quantities it specifies.

The flush option invokes a flush operation after a dump snapshot is written to the dump file. This insures the output in that file is current (no buffering by the OS), even if LAMMPS halts before the simulation completes.

Restrictions: none

Related commands:

dump, undump

Default:

The option defaults are format = %d and %g for each integer or floating point value, scale = yes, image = no, header = item, flush = no.