fix change/type command

Warning

GPU support for this command has not been tested and may not work as expected.

Syntax

fix ID group-ID change/type nevery nev n_rules nr rule rule1_keywords rule1_values rule rule2_keywords rule2_values ...

  • ID, is documented in fix command.

  • change/type = style name of this fix command

  • nevery = obligatory keyword

  • nev = check for rules every this many time-steps

  • n_rules = obligatory keyword

  • nr = number of rules defined afterwards

  • one or more rules may be appended

  • rule = obligatory keyword

  • zero or more rule_keyword/rule_value pairs may be appended

  • rule_keyword = atomtypes or region, where atomtypes is obligatory

atomtypes values = from_type ft to_type tt, where from_type and to_type are obligatory keywords and ft and tt the atom types for the rule
region value = ID of region atoms must be in to have type changed
heal value = auto_remove_duplicates or no
verbose value = yes or no

Examples

fix typechange all change/type nevery 50 n_rules 2  rule atomtypes from_type 1 to_type 2 region changereg1  rule atomtypes from_type 2 to_type 3 region changereg2

Description

This fix changes the atom type (material type) of atoms, based on a set of specified rules. These rules are checked periodically, as defined via the nevery keyword. If nevery = 1, then the check is performed every time-step. The number of rules is defined via the n_rules keyword.

Every rule consists of an atomtypes part and (optionally) a region part. The atomtypes part consists of a from_type and a to_type, i.e. particles that are of the atom type as specified by the from_type keyword, are converted to the atom type as specified by the to_type keyword. Note that this conversion (intentionally) implies that a different set of per-type properties will be associated to the atom. The set of properties defined by fix property/global / fix property/atomtype / fix property/atomtypepair will depend on the models you are using in the simulation. For a granular model, this would typically include frictional properties, cohesive properties or the coefficient of restitution.

If the optional region part is used, the type of atoms is only changed if they are in the specified region atoms at the time when the check is performed.

Restart, fix_modify, output, run start/stop

This fix writes no data to binary restart files. None of the fix_modify options are relevant to this fix. No global scalar or vector or per-atom quantities are stored by this fix for access by various output commands. No parameter of this fix can be used with the start/stop keywords of the run command.

Restrictions

none

Coarse-graining information:

Using coarsegraining in combination with this command should lead to statistically equivalent dynamics and system state.

Default

none