SAMOP 2021 – scientific programme
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MO: Fachverband Molekülphysik
MO 6: Ultrafast
MO 6.5: Talk
Thursday, September 23, 2021, 15:00–15:15, H2
Is CCSD(T) a proper standard for dipole moment calculations? An analysis considering diverse diatomic species — •Xiangyue Liu1, Laura McKemmish2, and Jesús Pérez-Ríos1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany — 2School of Chemistry, UNSW Sydney, Sydney, NSW 2052, Australia
Coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] is considered one of the most accurate electronic structure methods and has been widely used as a reference in benchmarking studies. The present work investigates the accuracy of CCSD(T) reproducing experimental ground state electric dipole moments and equilibrium distances of diatomic molecules. The results show that core-correlations are essential to some molecules, e.g., bi-alkali and main-group metal halides, to reach a satisfactory agreement with experimental measurements. However, for dipole moments of molecules involving transition metal atoms, CCSD(T) is not accurate enough even when including core-correlations. In addition, our work shows the relevance of using experimental data to benchmark theoretical quantum chemistry methods.