Relativistic calculations of AuSi+ and AuSi−

AbstractTheoretical calculations of the electronic structure of the ground state and a series of excited states of the AuSi+ and AuSi− molecules are presented. The calculations were carried out with the spin‐free relativistic infinite‐order two‐component (IOTC) method and high‐level complete active space self‐consistent field/complete active space perturbation theory correlated methods. The spin‐orbit (SO) coupling was introduced via the restricted active space state interaction method with the use of the atomic mean‐field SO integrals. The work presents the spectroscopic parameters of calculated states and full potential energy curves of the ionic AuSi+ and AuSi− structures for the first time. Electrostatic potential maps projected on the electron density surface illustrate the significant relativistic effects on going from nonrelativistic to scalar relativistic treatments.