Electron correlation effects of the ThO and ThS molecules in the spinor basis. A relativistic coupled cluster study of ground and excited states properties

TL;DR

This study uses relativistic coupled cluster methods to analyze the electronic structure, excited states, and electron correlation effects in ThO and ThS molecules, providing detailed spectroscopic data and ionization properties.

Contribution

It introduces a comprehensive relativistic coupled cluster approach with two FSCC variants to accurately model ground and excited states of ThO and ThS molecules.

Findings

Accurate bond lengths, excitation energies, and vibrational frequencies obtained.

Detailed analysis of electron correlation effects in ThO and ThS.

First ionization potential and electron affinity values reported.

Abstract

We present a comprehensive relativistic coupled cluster study of the electronic structures of the ThO and ThS molecules in the spinor basis. Specifically, we use the single-reference coupled cluster and the multi-reference Fock Space Coupled Cluster (FSCC) methods to model their ground and electronically-excited states. Two variants of the FSCC method have been investigated: (a) one where the electronic spectrum is obtained from sector (1,1) of the Fock space, and (b) another where the excited states come from the doubly attached electronic states to the doubly charged systems (ThO$^{2+}$ and ThS$^{2+}$), that is, from sector (0,2) of the Fock space. Our study provides a reliable set of spectroscopic parameters such as bond lengths, excitation energies, and vibrational frequencies, as well as a detailed analysis of the electron correlation effects in the ThO and ThS molecules. Finally, we examine the first ionization potential and electron affinity of the above mentioned molecules.