Guilin Sun
Ansys Employee

Unfortunately, 7 parameter-optimization is very challenge, it depends on the initial data, range, and generation size. Although I suggested to reduce the generation size and increase the generation number previously, it seems it is not effective, as the optimization stops at early generations even with small tolerance. In such case, you may need to do the other way: increase the generation size, but the generation number can be small from your practice, as they can always reach the defined tolerance. 

In addition, it might be localized for the optimization. You may need to change the parameter ranges since you already get some results and then redo the optimization. There might be many extremes.