TOPOLOGICAL FEATURES OF THE ELECTRON DENSITY DISTRIBUTION IN COVELLITE: POSITION Cu1
The synthesized sample of covellite was investigated by NQR 63,65Cu methods. The experimentally determined values of the quadrupole frequency νQ and the asymmetry parameter η have been used to study the distribution of electron density in the region of the quadrupole nuclei in position Cu1. It is found that Cu-S bond in position Cu1 is ionic, and the gap LUMO-HOMO decreases with increasing temperature.