Syntax:
mass I value
Examples:
mass 1 1.0 mass * 62.5 mass 2* 62.5
Description:
Set the mass for all atoms of one or more atom types. Mass values can also be set in the read_data data file. See the units command for what mass units to use.
I can be specified in one of two ways. An explicit numeric value can be used, as in the 1st example above. Or a wild-card asterik can be used to set the mass for multiple atom types. This takes the form "*" or "*n" or "n*" or "m*n". If N = the number of atom types, then an asterik with no numeric values means all types from 1 to N. A leading asterik means all types from 1 to n (inclusive). A trailing asterik means all types from n to N (inclusive). A middle asterik means all types from m to n (inclusive).
A line in a data file that specifies mass uses the exact same format as the arguments of the mass command in an input script, except that no wild-card asterik can be used. For example, under the "Masses" section of a data file, the line that corresponds to the 1st example above would be listed as
1 1.0
Restrictions:
This command must come after the simulation box is defined by a read_data, read_restart, or create_box command.
All masses must be defined before a simulation is run (if the atom style requires masses be set). They must also all be defined before a velocity or fix shake command is used.
Masses are not set for atom style granular. This is because each atom is assigned an individual mass in the data or restart file.
Related commands: none
Default: none