Dear Prof. Taylor,
thank you for your response.
I might have generated a confusion with my previous comment. Although the "periodic" boundary conditions were not in the "flat" file, but it is included in the input files for different domain by feap automatically.
At the moment, I would like to use the "link" command with parallel feap, which appears to be the main problem for me. In my applications, I will not use "periodic hill" from feap and will have a user defined loading, element and material routines.
I was wondering if there is any working example with only linking command, so that I can test my version.
Thank you for your help and sorry for any confusion.