Microsolvation of LiH+ in helium clusters: many-body effects and additivity models for the interaction forces

IONIC OH AS DOPANT OF HELIUM DROPLETS: AB INITIO POTENTIAL ENERGY SURFACES FOR OH+(3Σ-)-4He, OH-(1Σ-)-4He, AND STABLE STRUCTURES OF THEIR SMALLER CLUSTERS

Accurate, post-Hartree–Fock calculations have been carried out for a broad range of geometries in order to obtain an extended description of the orientational anisotropy and radial strength of the interaction of OH + and OH - ions with the unit species of a weak quantum solvent as that provided by 4 He droplets. The potential energy surfaces (PES) are obtained for the smallest complex system with one 4 He atom, and the possible role and importance of many-body effects is also investigated. The energetics and shapes of the OH +-4 He and OH --4 He internal bound states are obtained and analyzed in detail.

Ionic dimers in He droplets: Interaction potentials for Li2+–He,Na2+–He, and K2+–He and stability of the smaller clusters

We present post Hartree-Fock calculations of the potential energy surfaces (PESs) for the ground electronic states of the three alkali dimer ions Li(2) (+),Na(2) (+), and K(2) (+) interacting with neutral helium. The calculations were carried out for the frozen molecular equilibrium geometries and for an extensive range of the remaining two Jacobi coordinates, R and theta, for which a total of about 1000 points is generated for each surface. The corresponding raw data were then fitted numerically to produce analytic expressions for the three PESs, which were in turn employed to evaluate the bound states of the three trimers for their J=0 configurations: The final spatial features of such bound states are also discussed in detail. The possible behavior of additional systems with more helium atoms surrounding the ionic dopants is gleaned from further calculations on the structural stability of aggregates with up to six He atoms. The validity of a sum-of-potential approximation to yield realistic total energies of the smaller cluster is briefly discussed vis-a-vis the results from many-body calculations.

Ionic reactions in He nanodroplets: the [LiHHe]+ complex and its possible energy pathways into products from ab initio calculations

Ab initio calculations at the multiconfiguration self-consistent field level followed by a multireference configuration interaction were carried out along the two possible collinear approaches of the [LiHHe]+ system, while a three-dimensional calculation of the structures of that complex with LiH+ kept at its equilibrium geometry was also completed at the same level of accuracy. The interaction forces of the lowest two electronic states indicate possible reactive behavior, with the first excited potential-energy surface clearly showing a barrierless path to HeH+ product formation. The details of the reactive pathways and their possible bearing on reaction processes, which could occur at the low temperature of a He nanodroplet holding LiH+ as an impurity, are analyzed and discussed.