An ab initio study of the ground and valence excited states of GaF

Abstract

Ab initio calculations on the ground and valence excited states of the GaF molecule have been performed by using the internally contracted multireference electronic correlation methods (MR-CISD, MR-CISD + Q, and MR-AQCC) with entirely uncontracted all-electronic basis sets and Douglas-Kroll scalar relativistic correction. The potential energy curves of all valence states and the spectroscopic constants of bound states are fitted. It is the first time that the 12 valence Lambda-S states of GaF molecule and all of the 23 Omega states generated from the former are studied in a theoretical way. Calculation results well reproduce most of the experimental data. The effects of the size-extensivity correction and the avoided crossing rule between Omega states of the same symmetry are analyzed. The transition properties of the A 3Pi0+, B 3Pi1, C 1Pi1, and 3Sigma1+ states are predicted, including the transition dipole moments, the Franck-Condon factors and the radiative lifetimes. The radiative lifetime of the C 1Pi1 state of GaF molecule is of the order of nanosecond, implying that it is a rather short-live state. The lifetimes of the B 3Pi1 and 3Sigma1+ states are of the order of microsecond, while the lifetime of the A 3Pi0+ state are the order of millisecond.

Laser cooling of BH and GaF: insights from an ab initio study

“…Like BH, GaF also has highly diagonal FCFs ( f 00 = 0.997, f 11 = 0.989, f 22 = 0.958 and f 33 = 0.863) for the C 1 P (v 0 = j) -X 1 S + (v = i) transition, and the corresponding FCFs are presented in Table 5. Our computed FCFs are in good agreement with those of the results predicted by Yang et al 46 Thus, GaF meets the first criterion to be a potential laser cooling candidate.…”

“…14,45,62 For example, in comparison with experiments, 62 the calculated T e , R e , B e and D e are found to be accurate to better than 0.98%, 0.57%, 1.3% and 2.90%, respectively. The basis sets and CAS used in our calculations and those used in the results obtained by Yang et al 46 are almost the same; we find close agreement (B0.0015 Å for R e ) with all the three electronic states (X 1 S + , 3 P and C 1 P) computed in our present work. Overall, our present calculated spectroscopic constants give a good agreement with earlier theoretical and experimental data.…”

“…In 1990, Grabandt et al 37 measured the ionization energy of GaF using He(I) photoelectron spectroscopy. In 1991, the infrared emission spectrum of Dv = 1 bands of GaF was observed at 1000 1C with a resolution of 0.1 cm À1 by Uehara et al 38 In 1993, the millimeter wave rotational spectrum of GaF was studied in the 250-300 GHz frequency region by Hoeft et al 39 In 1995, new measurements of vibration-rotational absorption spectra of 69 Ga 19 F and 71 Ga 19 F were reported by Ogilvie et al 40 From a theoretical point of view, numerous theoretical calculations [41][42][43][44][45][46][47] have been performed on the electronic structure of the GaF molecule. In 1990, the Hartree-Fock-Slater type density-functional theory (DFT) calculations with a pseudopotential technique were carried out for GaF by Grabandt et al 37 In 1995, a comparison of the finite basis set with the finite difference Hartree-Fock (HF) calculations were performed on GaF by Kobus et al 41 In 1999, the contribution from correlations of the semi-core 3d electrons in Ga was studied by Mochizuki et al 42 In the same year, the scalar relativistic contribution to the atomization energies of GaF n were studied by Bauschlicher.…”

“…In 1990, the Hartree-Fock-Slater type density-functional theory (DFT) calculations with a pseudopotential technique were carried out for GaF by Grabandt et al 37 In 1995, a comparison of the finite basis set with the finite difference Hartree-Fock (HF) calculations were performed on GaF by Kobus et al 41 In 1999, the contribution from correlations of the semi-core 3d electrons in Ga was studied by Mochizuki et al 42 In the same year, the scalar relativistic contribution to the atomization energies of GaF n were studied by Bauschlicher. 43 In 2000, dipole, quadrupole, octupole, and hexadecapole moments were calculated for the ground states of sixteen diatomic species (including GaF) by Kobus et al 44 In 2002, the ground and the first excited states of gallium monohalides (GaX, X = F, Cl, Br, I) were calculated using DFT with different local density approximation (LDA) and general gradient approximations (GGA) by Yang et al 45 In 2004, the ground and valence excited states of GaF were studied by using the MRCI method with all-electronic basis sets and Douglas-Kroll scalar relativistic correction by Yang et al 46 In 2013, the ground electronic states of GaX (X = F, Cl, and Br) molecules were computed by Cao et al 47 As mentioned above, BH and GaF have been extensively studied in the past. In the present work, we focus on the theoretical studies of the laser cooling of BH and GaF molecules, though neither has yet been cooled.…”

Extensive ab initio study of the electronic states of SCl including spin-orbit coupling

“…As in our previous work, 1,2 we used the internally contracted multireference configuration interaction with single and double excitations plus Davidson correction [11][12][13] ͑MR-CISD+ Q͒ for single point energy calculations. At the present time, MR-CISD+ Q is still the most stable and reliable method for high accuracy calculation of electronic state structure, [14][15][16] especially for large bond length problems. PECs and spectroscopic constants were fitted after considering the avoided crossing rule between states of the same symmetry.…”