Relativistic calculations of AuSi+ and AuSi

• Published in: International journal of quantum chemistry Vol. 119; no. 16
• Main Authors: Barysz, Maria, Černušák, Ivan, Kellö, Vladimir
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.08.2019; Wiley Subscription Services, Inc
• Subjects: CASSCF/CASPT2/RASSI; Chemistry; Coupling (molecular); Electron density; Electronic structure; gold silicide ions; ground and excited states; Mathematical analysis; Perturbation theory; Physical chemistry; Potential energy; potential energy curves; Quantum physics; Relativism; Relativistic effects; relativistic infinite‐order two‐component method; spectroscopic parameters
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.25951

Theoretical 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. Relativistic calculations of the gold silicide cation and anion are reported for the first time. Potential energy curves, spectroscopic parameters, ionization energies, electron affinities, dissociation energies, and electrostatic potential (ESP, in atomic units) maps are presented. ESP maps show nicely significant relativistic effect manifested on going from nonrelativistic (NR) to scalar (Douglas‐Kroll‐Hess or IOTC) relativistic treatments.