Happy new year

This observation implies that the automatically determined bonding doesn't fulfill your expectation. You need to use $CHOOSE keyword to customize bonding relationship, please check NBO manual. All atoms directly or indirectly connected by "BD" will be regarded as a single fragment.

Best,

Tian

Hello. I hope you are doing well, and please accept my best wishes for the New Year.

I would like to ask you a question regarding NBO. In some cases, NBO does not correctly identify the fragments of the system under study. For example, in a system where we clearly have three completely independent fragments, NBO sometimes recognizes only two fragments, or it fails to correctly assign atoms to their proper fragments. As a result, the subsequent analyses and calculations can become entirely unreliable.

If possible, I would greatly appreciate your guidance on how one can explicitly define the number of fragments and the atoms belonging to each fragment manually, at the stage of generating the .47 file using Gaussian16 C.02 and the "pop=nboread" keyword.

With my sincere thanks and best regards,
Saeed