Modeling of photoabsorption spectra of small helium cluster cations through ab initio and semi-empirical approaches. A comparative study

Size Evolution of Photoabsorption Spectra of Small Clusters: A Computational Study

“…However, in the light of the results of Ref. [10], it is not clear how realistic these estimates can be considered for very weakly polarizable helium atoms. As a consequence, the polarization correction of Ref.…”

“…The analysis presented in Ref. [10] shows thus that the DIM method is fully adequate for the description of the electronic structure of the He þ N clusters and that a failure of the DIM method may not be the root of the observed discrepancy between theoretical predictions and experimental measurements of the He þ 10 photoabsorption spectra. This conclusion, enhancing our trust in the DIM model for He þ N , was another motivation for us to perform the series of additional calculations focusing on the evolution of He þ N photoabsorption spectra with the cluster size.…”

“…As a first step, a verification of the electronic structure model used in the previous work (the DIM model) was performed by comparing it with more sophisticated models of high-level ab initio approaches (MRCI and EOM). [10] Such a comparison, however, showed that the DIM model provided an accuracy comparable with that of the used ab initio methods.…”

“…An ideal, though indirect marker of the evolution of the ionic core with cluster size is the cluster photoabsorption spectrum since the ionic core acts as an efficient chromophore. Despite this, however, just a couple of experimental [7] and theoretical [8–10] studies of $${{{\rm H}{\rm e}}_{N}^{+}}$$ photoabsorption have been published up to now.…”

“…The disagreement seen between the simulations [9] performed for $${{{\rm H}{\rm e}}_{10}^{+}}$$ and corresponding experimental data [7] led us to additional efforts aiming at disclosing possible sources of the observed discrepancy. As a first step, a verification of the electronic structure model used in the previous work (the DIM model) was performed by comparing it with more sophisticated models of high‐level ab initio approaches (MRCI and EOM) [10] . Such a comparison, however, showed that the DIM model provided an accuracy comparable with that of the used ab initio methods.…”