NBO executable for QChem

Is QChem limited to the nbo7.i4.exe or is the nbo7.i8.exe supported?

Hello Jim,

Thank you for the question. Technically, Q-Chem only supports NBO5, which is shipped with Q-Chem. However, you may find find some working examples for NBO6 (https://dx.doi.org/10.1002/wcms.51) and NBO7(https://dx.doi.org/10.1002/jcc.25873). If there are no major changes bewtween nbo7.i4 and nbo7.i8, I assume they should work.

Actually what Kuan-Yu said is not quite right. NBO5 (and only v. 5) ships with Q-Chem, but we do support NBO6 and 7 as a external program that can be passed information from Q-Chem, as described in the manual: Q-Chem 4.3 User’s Manual : Interface to the NBO Package

If the information that is required from the electronic structure program did not change between i4 and i8 (and I strongly suspect that it did not), then there should be no difference.

Unfortunately, with input that works for the nbo7.i4 version, the nbo.i8 version hangs, even after applying the system patches mentioned in other Q-Chem forum postings.

It appears Q-Chem interface for the NBO7 program was created using the i4 interface, not the i8.

Ok. Please submit a bug report to Q-Chem, this probably requires us to contact NBO developers to figure it out.

Thank you for your reply.

I have discussed this problem with Eric Glendening of the NBO group. Eric indicated Q-Chem developers chose to use the i4 version of NBO7 for ‘integration’ with NBO7.

The developers would need to redo the NBO7 integration using the i8 code.

The i8 code is accessible if one uses gennbo and a Q-Chem generated FILE.47.