Multireference Wavefunction-Based Investigation of the Ground and Excited States of LrF and LrO

Abstract

Complete active space self-consistent field (CASSCF) and multireference configuration interaction with Davidson correction (MRCI+Q) calculations have been carried out for lawrencium fluoride (LrF) and lawrencium oxide (LrO) molecules, detailing 19 and 20 electronic states for LrF and LrO, respectively. For LrF, two dissociation channels were considered, Lr( 2 P)+F( 2 P) and Lr( 2 D)+F( 2 P). However, due to the more complex electronic manifold of LrO, three dissociation channels were computed: Lr( 2 P)+O( 3 P), Lr( 2 D)+O( 3 P), and Lr( 2 P)+O( 1 D). In addition, equilibrium bond lengths, harmonic vibrational frequencies ω e , anharmonicity constants ω e χ e , ΔG 1/2 values, and excitation energies T e for the ground and several excited electronic states were calculated for both molecules, for the first time. Bond dissociation energies (BDEs) were calculated for LrF and LrO using several different levels of theory: unrestricted coupled-cluster with single, double, and perturbative triple excitations (UCCSD(T)), density functional theory (B3LYP, TPSS, M06-L, and PBE), and the correlation-consistent composite approach developed for f-elements (f-ccCA).

Population analysis and the effects of Gaussian basis set quality and quantum mechanical approach: main group through heavy element species

“…This charge is approximately 0.30 e larger than that found in this work using HF/cc-pVQZ-DK3 ( Figure 10A ). The ground state electronic structure for this molecule is a closed-shell singlet ( 1 Σ + ) that is well separated (∼22,225 cm -1 ) from the first excited state, according to recent work done using the multireference configuration interaction method with a Davidson correction (MRCI + Q) ( North et al, 2023 ). For heavy element species, it is important to include relativistic effects in both the basis set and Hamiltonian.…”

MQM 2022: The 10th Triennial Conference on Molecular Quantum Mechanics

“…The ultimate goal of all theoretical and methodological developments in quantum chemistry is to apply the new tools and techniques to important problems in molecular and materials science. North and co-workers in the Wilson group at Michigan State University carried out multireference  complete active space self-consistent field (CASSCF) and MRCI  calculations on lawrencium fluoride and oxide molecules to obtain detailed spectroscopic information for numerous electronic states . In addition, they obtained bond dissociation energies using a range of quantum chemical methods.…”