Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (8): 1447-1455.doi: 10.3866/PKU.WHXB201405302

• THEORETICAL AND COMPUTATIONAL CHEMISTRY • Previous Articles     Next Articles

Theoretical Studies on Low-Lying States of AuX (X=O, S)

LIANG Yan-Ni1, WANG Fan2   

  1. 1. College of Chemistry, Sichuan University, Chengdu 610065, P. R. China;
    2. Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, P. R. China
  • Received:2014-04-11 Revised:2014-05-29 Published:2014-07-18
  • Contact: WANG Fan E-mail:wangf44@gmail.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21273155).

Abstract:

Multireference approaches have commonly been employed to calculate low-lying states of openshell molecules with spin-orbit coupling (SOC), such as for AuO and AuS. However, by choosing a proper reference state, the equation-of-motion coupled-cluster approach (EOM-CC) can also be used to calculate some low-lying states of these molecules. Furthermore, the EOM-CC approach is a single-reference method and, therefore, more easily employed than multireference approaches. In this work, low-lying states of AuO and AuS are investigated based on a recently developed EOM-CC approach for ionization potentials (EOMIP-CC) with SOC at the CCSD level, using the corresponding anions as reference. The contribution of triples with EOMIPCC is estimated by comparing results of EOMIP-CCSD and EOMIP-CCSDT at a scalar relativistic level. In addition, compared with the EOMIP-CCSDT results, errors by UCCSD(T) can reach 0.1-0.15 eV when spin contamination is significant and the norm of T1 is sizeable. When SOC is present, bond lengths and harmonic frequencies obtained with EOMIP-CCSD for the investigated states are in reasonable agreement with experimental data. Furthermore, ionization energies corresponding to the high-lying 2Δ3/2, 2Σ1/2+, and 2Π1/2 states are overestimated by EOMIP-SOC-CCSD, but results for the other low- lying states agree well with the experimental data, with an error of approximately 0.2 eV. These results indicate that the single-reference EOMIPCCSD method with SOC is able to provide a reasonable description of low-lying states of AuO and AuS.

Key words: Spin-orbit coupling, Equation-of-motion coupled-cluster approach, Ionization energy

MSC2000: 

  • O641