First principles study of cobalt hydride, CoH, and its ions CoH+ and CoH−

Abstract

The electronic structure of the diatomic species CoH, CoH(+), and CoH(-) have been studied mainly by multireference configuration interaction (MRCI) methods and basis sets of quintuple quality. The restricted coupled-cluster with iterative singles + doubles + quasi-perturbative connected triples, RCCSD(T), approach was also employed, limited however to the ground states only. At the MRCI level we have constructed 27 (CoH), 24 (CoH(+)), and 12 (CoH(-)) potential energy curves correlating adiabatically to six, seven, and two energy channels, respectively. For the ground states scalar relativistic and core-subvalence effects have been taken into account. We report energetics, spectroscopic parameters, dipole moments, excitation energies, and spin-orbit coupling constants. Our CoH calculated results are in accord with experiment, but there is an interesting discrepancy between theory and experiment concerning the dipole moment, the former being significantly larger than the latter. Experimental results on CoH(+) and CoH(-) are scarce. The ground state of CoH, CoH(+), and CoH(-) are definitely of (3)Φ, (4)Φ, and (4)Φ symmetries with calculated (experimental) dissociation energies D(0)(0) = 46.4 ± 0.5(45.0 ± 1.2), 49.6(47 ± 2), and 45.6(43.1 ± 1.2) kcal/mol, respectively. In all 24 calculated CoH states, a Co-to-H charge transfer of 0.2-0.3 e(-) is recorded; in CoH(-), however, the negative charge resides almost exclusively on the Co atom.

Controlling the Spin of Co Atoms on Pt(111) by Hydrogen Adsorption

“…A ground state with S eff ¼ 2 is quite surprising for the CoH complex, with its S eff being even higher than the spin of a free Co atom. Calculations for the free CoH molecules predict a S ¼ 1 ground state multiplet, with the antiparallel coupling between the spins of the Co (S ¼ 3=2) and the H atom (S ¼ 1=2) [19]. These calculations further show that ferromagnetic alignment yielding the observed S ¼ 2 becomes favored only upon an increase of the Co-H bond length by 10%.…”

“…These calculations reveal a significant change of the magnetic properties through hydrogenation, with a clear tendency of decreasing spin with increasing number of H atoms [17][18][19]. This results from the antiparallel spin alignment between metal and H. In particular, for the case of Co, the spin S ¼ 3=2 of the free atom is reduced to 1 and 1=2 upon the adsorption of one and two hydrogen atoms, respectively [17][18][19].…”

“…These calculations reveal a significant change of the magnetic properties through hydrogenation, with a clear tendency of decreasing spin with increasing number of H atoms [17][18][19]. This results from the antiparallel spin alignment between metal and H. In particular, for the case of Co, the spin S ¼ 3=2 of the free atom is reduced to 1 and 1=2 upon the adsorption of one and two hydrogen atoms, respectively [17][18][19].The effect of hydrogen adsorption on the spin of surfaceadsorbed magnetic atoms is largely unknown. Hints that the spin possibly changes upon H adsorption can be inferred from the H-induced appearance [14] or disappearance [13,15] of the Kondo effect.…”

Computational study of adsorption of cobalt on benzene and coronene

“…[33]. A similar profusion of states can be expected to exist in the interaction of cobalt with graphene.…”

Ab initiocalculations to support accurate modelling of the rovibronic spectroscopy calculations of vanadium monoxide (VO)

“…Other 3d transition-metal/first-row-atom diatomic species have proven to have similar challenges. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] These studies illustrate the power of the MRCI approach, which has consistently been shown to be a reasonably robust way of investigating low-lying excited states of these systems to usually at least semi-quantitative accuracy when compared against experiment. However, the studies also demonstrate the limitations of even these very high accuracy methods, e.g.…”