I have many PDB files and would like to calculate affinity prediction of a particular metal ion (in kcal/mol) for each of them. Can you suggest a software suitable for my purpose?

Thanks.

(1)I tried FoldX and had very hard time working with it.

(2) I posted a question Improved Metal Binding Upon Amino Acid Change which was much broader, and didn't get answer. I figured out some part of it, and still trying to figure out affinity part.