4.2 Population

variable populationSize

Meaning: The number of structures in each generation; initial generation can be set separately, if needed.

Default: rounded to the closest 10, where is the number of atoms/cell (or maxAt for variable composition). The upper limit is 60. Usually, you can trust these default settings.

Format:

20 : populationSize

variable initialPopSize

Meaning: The number of structures in the initial generation.

Default: equal to populationSize.

Format:

20 : initialPopSize

Note: In most situations, we suggest that these two parameters be equal. Sometimes (especially in variable-composition calculations) it may be useful to specify initialPopSize to be larger than populationSize. It is also possible to have a smaller initial population, and this is useful if one wants to generate the first population entirely from a few seed structures.

variable numGenerations

Meaning: Maximum number of generations allowed for the simulation. The simulation can terminate earlier, if the same best structure remains unchanged for stopCrit generations.

Default: 100

Format:

50 : numGenerations

variable stopCrit

Meaning: The simulation is stopped if the best structure did not change for stopCrit generations, or when numGenerations have expired — whichever happens first.

Default: total number of atoms for fixed-composition runs, maximum number of atoms maxAt for variable-composition runs.

Format:

20 : stopCrit