Born effective charge can be obtained from CASTEP code by running phonon calculation,

Thanks Mr. Mohammed M. Obeid. I performed phonon calculations via CASTEP, but i don't know that how to interpretate the Born effective charge. Can you please provide me some reference data from phonon calculation that show the Born effective charge?

After your software "successful completed", you can find a lot of results as shown in the attached file below (search for "Born effective charge") , one of these results is Born effective charge. you have to find closer results to your crystal system so you can compare you results precisely. secondly, you can find huge data everywhere about BEC, please check the attached PDF too.

Thanks Mr. Mohammed M. Obeid for this valuable answer.

Dr. Mohammed Obeid : Thank you for this valuable answer.

you should calculate phonon dispersion. Then, in the output file, you will see Born effective charge.