Nitrogen-pair paramagnetic defects in diamond: A density functional study

Abstract

The N1, W7, M2, N4, M3, and NOC1-4 electron-paramagnetic-resonance centers in diamond have been assigned to pairs of nitrogen donors separated by different numbers of intervening host sites, both in ionized, $S=1/2$, and neutral $S=1$ forms. Using density functional techniques, we confirm these models, but in order to do so for the N4 center we show that it is essential that extremely low energy reorientation takes place. We also show that charge exchange and chemical rebonding effects provide an explanation for the distinct forms of $S=1$, neutral configurations observed.