Addition

An atom type whose current count does not exceed the limit specified by ul_nat is randomly selected, and one atom of that type is added at a random position.

• One atom is added, and if it does not violate the minimum interatomic distance defined by mindist, the structure is accepted.
• If the distance condition is not satisfied, the atom is placed again at a different random position. This process is repeated up to maxcnt_ea times.
• If no valid offspring is obtained, the volume is expanded by 10%, and the same procedure is retried up to maxcnt_ea times.
• If that also fails, the volume is expanded up to 20% and the structure generation is attempted again. If it still fails, the parent is replaced.