Theoretical study of low-lying electronic states of BiN, BiP, BiAs, and BiSb

Calculation of electric field gradients with the exact two-component (X2C) quasi-relativistic method and its local approximations

“…Theoretical spectroscopic studies of BiN and BiP show that their ground Ω state X 0 + is predominantly X 1 Σ + mixed with a minor contribution from 3 Π 0+ , which, upon re-normalization, amounts to only 4%. 94,95 Because the NQCC of 3 Π has an opposite sign to that of X 1 Σ + , the corrected MR-AQCC NQCC value of X 0 + decreases to 908 for BiN and 900 MHz for BiP with the approximate inclusion of SOC, which is very close to the experimental and highly-accurate theoretical values from the literature.…”