I found that model.write_data() ignores mercury ions (HG) when writing .ngh files (e.g. 1AVN.pdb, 1OKM.pdb).

It also ignores UNX (UNKNOWN ATOM OR ION), in which case I understand.

I checked whether mercury ions are ignored because it's not in modeller-9v8/modlib/restyp.lib,

but I don't think so because LI1 (in 2I21.pdb) and DOD (in 1CQ2.pdb) are not ignored.

Is there a reason why mercury ions should be ignored? Are there any other specific records that model.write_data() will ignore?

Thank you!

- Yingjie