One-Electron Pseudo-Potential Determination of Stable Isomers of the Li*Ar n Excited Clusters: Absorption Spectra

Abstract

We present pseudo-potential calculations of geometrical structures of stable isomers of LiAr n clusters with both an electronic ground state and excited states of the lithium atom. The Li atom is perturbed by argon atoms in LiAr n clusters. Its electronic structure obtained as the eigenfunctions of a single-electron operator describing the electron in the field of a Li ? Ar n core, the Li ? and Ar atoms are replaced by pseudo-potentials. These pseudo-potentials include core-polarization operators to account for the polarization and correlation of the inert core with the valence Lithium electron [J Chem Phys 116, 1839 1]. The geometry optimization of the ground and excited states of LiAr n (n = 1-12) clusters is carried out via the Basin-Hopping method of Wales et al. [J Phys Chem 101, 5111 2; J Chem Phys 285, 1368 3]. The geometries of the ground and ionic states of LiAr n clusters were used to determine the energy of the high excited states of the neutral LiAr n clusters. The variation of the excited state energies of LiAr n clusters as a function of the number of argon atoms shows an approximate Rydberg character, corresponding to the picture of an excited electron surrounding an ionic cluster core, is already reached for the 3s state. The result of optical transitions calculations shows that the absorption spectral features are sensitive to isomer structure. It is clearly the case for transitions close to the 2p levels of Li which are distorted by the cluster environment.

Absorption Spectroscopy, a Tool for Probing Local Structures and the Onset of Large-Amplitude Motions in Small KArn Clusters at Increasing Temperatures

“…The isomers of low energy that were found in the present work are shown in Figure 1. Their structure is similar to that reported for LiAr n 23 and NaAr n 22 clusters. Except for the lowest isomer of KAr 10 , K is indeed located at the surface of a close-pack Ar cluster.…”

“…The electron problem thus reduces in alkali-rare clusters to that of a single electron (the valence electron of the alkali atom) and can be treated very simply at the Hartree–Fock level. This methodology, which we call the one-electron model, was recently applied to simulate the absorption spectrum of Li and Na in small argon clusters. , …”

“…This methodology, which we call the one-electron model, was recently applied to simulate the absorption spectrum of Li and Na in small argon clusters. 22,23 The present work associates the one-electron model to an MC exploration of the ground-state phase space to simulate the absorption spectrum of a single potassium atom bound to a few argon atoms. These spectra, used as a tool to explore local structures about the K atom and the onset of large-amplitude motions in KAr n (n = 1−10) clusters, are simulated at cluster temperatures between 2 and 25 K.…”

Computational study of the electronic structure of the Srm+Kr (m = 0, 1) van der Waals complexes

“…Then, we achieved one and two-electron calculations of the electronic states of the Sr + Kr and SrKr molecules, respectively. For the SrKr diatomic molecules, we employed a full Configurations Interaction (full-CI) employing the CIPSI algorithm, (Configuration Interaction by Perturbation of a multi-configuration wave function Selected Iteratively) [59][60][61][62][63].…”

“…The hamiltonian for the Sr + Kr and SrKr molecular systems is described by the following equation [61,62]:…”