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.
Most atom styles require masses to be specified. One exception is atom_style granular, where masses are defined for individual atoms, not types. Pair_style eam defines the masses of atom types in the EAM potential file.
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 asterisk 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 asterisk with no numeric values means all types from 1 to N. A leading asterisk means all types from 1 to n (inclusive). A trailing asterisk means all types from n to N (inclusive). A middle asterisk means all types from m to n (inclusive).
A line in a data file that specifies mass uses the same format as the arguments of the mass command in an input script, except that no wild-card asterisk 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.
Related commands: none
Default: none