Potential energy curves via double ionization potential calculations: example of 1,2-diazene molecule

摘要

The equation-of-motion coupled-cluster (CC) approach in the version suitable for the double ionization potential (DIP) calculations has been applied to compute torsional potential energy curves (PECs) for the ground and excited states of the 1,2-diazene system. The ground state of the latter molecule exhibits an appreciable multireference character for the twisted conformations and therefore the standard CC approaches fail to describe correctly the torsional PECs for the ground and excited states. The DIP approach, based on the double anion reference—dominated by single configuration in the whole range of dihedral angle—provides smooth and cusp-free potential energy curves.