Molecular study of theH+-Kr collisional system

Ab initio calculations have been performed to provide the basis for a molecular study of the elastic and the lowest charge-transfer channels in ${\mathrm{H}}^{+}$ + Kr collisions. The adiabatic ground-state potential-energy curve agrees satisfactorily with that predicted from elastic scattering experiments. In the Hartree-Fock treatment, the charge transfer into $\mathrm{H}\left(1\mathrm{}s\right)+{\mathrm{Kr}}^{+}\left(4\mathrm{}{p}^5\right)$ appears to be mainly caused by a double virtual electronic transition via a doubly excited state. A "projected valence bond" (PVB) treatment involving single-configuration diabatic states built from projected H and Kr atomic orbitals is also presented. With such diabatic states the charge-exchange process is suitably described as occurring directly under the effect of an exponentially decreasing coupling between closely lying and almost parallel energy curves. The defects of the PVB approximation arising at small internuclear distances ($R$) are discussed. Diabatic states for the spin-orbit coupling are suggested for studying the population sharing between the $\Omega =0^{+}$ states dissociating into $\mathrm{H}+{\mathrm{Kr}}^{+}(4\mathrm{}{p}^5:{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{},{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{})$. A procedure involving a basis change from the adiabatic states at small $R$ to the PVB states at large $R$, together with the diabatic states for spin-orbit coupling is proposed to solve effectively the relevant scattering close-coupling equations.