Communication: Electric properties of the ThO(X Σ1+) molecule

Abstract

To assist the proposed search for the electric dipole moment of the electron with the thorium oxide, converged ab initio coupled cluster calculations are performed on the interaction energy, dipole moment, anisotropic static dipole polarizability, and quadrupole moment of the ThO(X Σ1+) molecule as functions of internuclear distance. The rovibrational energy levels and wave functions are computed to derive the spectroscopic constants and matrix elements of electric properties. Ab initio calculations provide good agreement with the measured spectroscopic constants but call for a revision of the dissociation energy estimates from mass-spectrometric measurements and previous calculations.

Communication: The permanent electric dipole moment of thorium monoxide, ThO

“…The determined parameters are (in wavenumbers, cm 1 + (v = 0) state (=1.842 17 Å) is identical to that determined from the pure rotational spectrum 7 and slightly smaller than the recent ab initio prediction of 1.846 Å. 10 The R value for E(0…”

“…The field-free transition wavenumbers of Table I were least squares fit to a model that included the upper and lower state rotational parameters, B, and the band origin, T 10 . The determined parameters are (in wavenumbers, cm 1 + (v = 0) state (=1.842 17 Å) is identical to that determined from the pure rotational spectrum 7 and slightly smaller than the recent ab initio prediction of 1.846 Å.…”

He–ThO(1Σ+) interactions at low temperatures: Elastic and inelastic collisions, transport properties, and complex formation in cold 4He gas

“…41 The O(1s 2 ) and Th(5s 2 5 p 6 5d 10 ) atomic orbitals were included in the core. As shown by a detailed analysis of the monomer electric properties, 6 this basis set is not fully saturated, which may lead to underestimation of the induction and dispersion interactions within the complex. To correct this problem, we placed a set of bond functions 3s3 p2d2 f 1g (Ref.…”

“…Because the vibrational frequency of ThO (896 cm −1 ) (Ref. 36) is large compared to all other energy scales of interest in this work, we fixed the ThO internuclear distance at r e = 1.845 Å, as estimated from converged calculations on the monomer 6 (the measured Born-Oppenheimer equilibrium distance 37 is slightly smaller, 1.8402 Å). The rotational constant B e of ThO was taken as 0.332 cm −1 .…”

“…Previous theoretical work has established that the electronic wave function of the X 1 + state of ThO at r ≈ r e can be accurately described within the scalar-relativistic singlereference coupled cluster method. 6 The same method was implemented here in its restricted version with singles, doubles, and noniterative triples [CCSD(T)] based on the standard restricted Hartree-Fock (RHF) reference. 38 We employed a small-core relativistic effective core potential ECP60MWB (Ref.…”