d-dtransfer in transition-metal monoxides and dihalides

It is pointed out that some qualitative differences exist in the upper d-band edge of the observed uv photoemission spectra among the insulating transition-metal monoxides (TMO's) and dihalides (TMH's), MnO, NiO, MnCl₂, and NiCl₂. On the basis of band-structure calculations, we interpret this fact as a manifestation of the significance of the d-d hopping in TMO's. In relation to this, we predict that photoemission and inverse photoemission spectra will show significant changes for TMO's as the measuring temperature crosses the N\'eel temperature, but virtually no change for TMH's.