DIM modelings for realistic simulations of ionic rare-gas clusters, test on structures and photoabsorption spectra of Arn+ (n=3–8)

Photodissociation dynamics of ionic argon pentamer

“…In this case, only monomers are produced in experiments [16] with a bimodal kinetic energy distribution (fast and slow fragments) both for neutrals and for ions. Our earlier [6,13,[17][18][19][20] as well as recent [14,15] theoretical simulations have nicely reproduced these experimental findings and showed that, in visible excitation, the trimer, initially almost linear and symmetric, mainly explodes leaving the central atom to rest in the center-of-mass. Interestingly, for the higher photon energies, the ions are produced in the high fine-structure state [15] corroborating the experimental findings [16].…”

“…A couple of additional corrections can further be included in the original DIM model, namely the leading polarization [3] and dispersion [26] three-body forces, which advance the DIM model beyond the purely pair-wise additive level. Since such corrections do not seem important for small ionic clusters of argon [6], they are not considered here to reduce computational demands [27]. In the extended DIM+SO model, the electronic Hamiltonian matrix of an Rg + N cluster is a 6N × 6N matrix (30 × 30 for Ar + 5 ) and the lowest 3N (15 for Ar + 5 ) doubly degenerate electronic states can be obtained by diagonalizing it.…”

“…In this work we use the diatomic curves for Ar + 2 taken from ab initio calculations [28], a state-of-the-art semiempirical potential for neutral Ar 2 [29], and the spin-orbit coupling constant extracted from experimental data on the splitting between the 2 P 1/2 and 2 P 3/2 fine-structure states of Ar + [30]. The DIM+SO model used in this work has many times been tested successfully against available experimental data on small and medium-size argon clusters, including their structures and energetics [6,31], photoabsorption [6], and non-adiabatic dynamics [14,15,32], and can, thus, be considered well established for the description of intra-cluster interactions in these clusters.…”

“…24 for details). In this work, we use two of them: a) the method combining the AMP approach for calculating the collapse probabilities and the S algorithm for adjusting nuclear velocities as that developed previously and tested in numerous photoabsorption modelings on raregas cluster cations, including argon [6,14]. The methodology is based on the point-charge approximation [34] combined with the inclusion of atomic polarization effects [35].…”

“…As clusters, they are aimed to improve the understanding of the transition between the gas and the condensed phases of matter [1]. Although made of identical atoms, the charge is localized on a small chromophoric subunit [2][3][4][5][6], mainly trimer, but also tetramer or dimer, while the surrounding atoms are almost neutral. Therefore the rare-gas clusters are bound by heterogeneous interactions, like solvated species, with strong chemical interactions between the core atoms and loosely bound neutrals.…”