Issue 35, 2024

Wavefunction theory and density functional theory analysis of ground and excited electronic states of TaB and WB

Abstract

Several low-lying electronic states of TaB and WB molecules were studied using ab initio multireference configuration interaction (MRCI), Davidson corrected MRCI (MRCI+Q), and coupled cluster singles doubles and perturbative triples [CCSD(T)] methods. Their full potential energy curves (PECs), equilibrium electron configurations, equilibrium bond distances (res), dissociation energies (Des), excitation energies (Tes), harmonic vibrational frequencies (ωes), and anharmonicities (ωexes) are reported. The MRCI dipole moment curves (DMCs) of the first 5 electronic states of both TaB and WB are also reported and the equilibrium dipole moment (μ) values are compared with the CCSD(T) μ values. The most stable 13Π (1σ2213) and 15Δ (1σ22121) electronic states of TaB lie close in energy with ∼62 kcal mol−1De with respect to the Ta(4F) + B(2P) asymptote. However, spin–orbit coupling effects make the 15Δ0+ state the true ground state of TaB. The ground electronic state of WB (16Π) has the 1σ21132 electron configuration and is followed by the excited 16Σ+ and 14Δ states. Finally, the MRCI De, re, ωe, and ωexe values of the 13Π state of TaB and 16Π and 14Δ states of WB are used to assess the density functional theory (DFT) errors on a series of exchange–correlation functionals that span multiple-rungs of the Jacob's ladder of density functional approximations (DFA).

Graphical abstract: Wavefunction theory and density functional theory analysis of ground and excited electronic states of TaB and WB

Supplementary files

Article information

Article type
Paper
Submitted
28 May 2024
Accepted
25 Jul 2024
First published
25 Jul 2024
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2024,26, 22858-22869

Wavefunction theory and density functional theory analysis of ground and excited electronic states of TaB and WB

I. R. Ariyarathna, Phys. Chem. Chem. Phys., 2024, 26, 22858 DOI: 10.1039/D4CP02202E

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