Abstract
We studied theoretically the structure and stability of the Helium atom interacting with the diatomic system K-2(+)(X-2 Sigma(+)(g)). The calculations carried out using an accurate ab initio calculation based on the pseudo-potential approach and for an extensive range of the remaining two Jacobi coordinates, R and theta. The pseudo-potential method has reduced the number of active electrons of the He-K-2(+)(X-2 Sigma(+)(g)) van der Waals complex to only one electron. The potential energy surfaces determined and used to extract the spectroscopic data related to the stability of the He-K-2(+)(X-2 Sigma(+)(g)) van der Waals complex. The results show that the He-K-2(+)(X-2 Sigma(+)(g)) van der Waals complex is more stable in the linear geometry and the Helium atom does not perturb the stretching mode of K-2(+)(X-2 Sigma(+)(g)).