Ground State Of HeH Research Articles

Photodissociation from the ground state of HeH+: comparison with experiment

We investigate the photodissociation process for both hot and cold HeH+ ions. Detailed comparison with experiments performed at FLASH is made possible by experimentally determining the ro-vibrational distribution of the ions under identical source conditions, and averaging the theoretical cross sections accordingly.

Ab initio calculation of proton scattering from He(1s2s, 1S): a first-principles wavepacket study beyond the Born-Oppenheimer approximation

A first-principles study of the scattering of protons from the lowest-metastable singlet state of He, He(1s2s, 1S) is reported. The ground state of HeH+ and the four lowest excited states of 1 symmetry are treated by means of full configuration-interaction (FCI) calculations in an extended basis set. From the adiabatic potential curves diabatic potentials and diabatic coupling elements are generated by means of a block-diagonalization scheme. Hartree-Fock orbitals, frozen orbitals and state-averaged natural orbitals are used for generating CI wavefunctions as well as for the quasi-diabatization. The diabatic potential curves and the off-diagonal coupling elements are used in wavepacket calculations to simulate the scattering of protons and deuterons from 4He(1s2s, 1S) and 3He(1s2s, 1S).

Experimental Born–Oppenheimer Potential for theX1Σ+Ground State of HeH+: Comparison with theAb InitioPotential

All literature on vibration–rotational and pure rotational transition energies for theX1Σ+state of4HeH+,3HeH+,4HeD+, and3HeD+have been employed in a direct least-squares fit of the radially dependent Hamiltonian. The Born–Oppenheimer potential is represented by a modified Lennard–Jones function that provides for correct behavior in the near dissociation long-range region. Only 19 adjustable parameters were required to represent the 166 measured transition energies, which are reproduced almost to within the measurement accuracies. The fitted potential and Born–Oppenheimer breakdown functions are shown to be in good agreement with the results ofab initiocalculations. The results are used to obtain high-order centrifugal distortion constants as well as level widths for quasi-bound levels.

Complete Cl calculations on the ground state of HeH

Complete Cl calculations on the van der Waals molecule HeH with a large Gaussian basis set give the depth of the potential well as c = 0.50 meV and a minimum at R m = 3.64 Å. An analytical function has been fitted to the ab initio points and to the best estimates of the dispersion energy coefficients. One further parameter in the potential has been chosen to reproduce the HeH scattering cross section.

Semi-localized orbitals for the ground state of HeH+

Semi-localized orbitals for the ground state of HeH⁺