Probing Electronic Wave Functions of Sodium-Doped Clusters: Dyson Orbitals, Anisotropy Parameters, and Ionization Cross-Sections

Abstract

We apply high-level ab initio methods to describe the electronic structure of small clusters of ammonia and dimethyl ether (DME) doped with sodium, which provide a model for solvated electrons. We investigate the effect of the solvent and cluster size on the electronic states. We consider both energies and properties, with a focus on the shape of the electronic wave function and the related experimental observables such as photoelectron angular distributions. The central quantity in modeling photoionization experiments is the Dyson orbital, which describes the difference between the initial N-electron and final (N-1)-electron states of a system. Dyson orbitals enter the expression of the photoelectron matrix element, which determines total and partial photoionization cross-sections. We compute Dyson orbitals for the Na(NH) and Na(DME) clusters using correlated wave functions (obtained with equation-of-motion coupled-cluster model for electron attachment with single and double substitutions) and compare them with more approximate Hartree-Fock and Kohn-Sham orbitals. We also analyze the effect of correlation and basis sets on the shapes of Dyson orbitals and the experimental observables.

Vacuum ultraviolet photoionization cross section of the hydroxyl radical

“…41,42 For photoionization or photodetachment from open-shell doublet species producing a closed-shell state, one can employ the reference state corresponding to the ionized closed-shell state and use EOM-EA (EOM for electron attachment, where the EOM operators add an electron to the reference) to describe the initial doublet state. 43 In the case of photoionization of O( 3 P) and OH( 2 Π), however, both the initial and the final states are of open-shell character (see Fig. 1).…”

Multi-reference protocol for (auto)ionization spectra: Application to molecules

“…[36][37][38][39][40][41] Here, the simplest approach is to model the outgoing electron as a free particle or a distorted wave corresponding to an effective Coulomb potential, [42][43][44] which has been in particular applied to PES studies of rather large molecules. [45][46][47][48][49] Finally, an entirely different set of methods relies on an implicit continuum representation with Stieltjes imaging [50][51][52][53] or a Green's operator formalism. 54 However, energies of several hundreds of eV, targeted in X-ray PES and RAES necessitate large basis sets leading to demanding computations.…”

Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters

“…Magic numbers play a central role in cluster science (see references on molecular clusters [1][2][3][4][5][6][7][8][9][10][11][12] ). Usually, these magic numbers are related to the high stability of clusters of certain sizes.…”

“…10,11,13,14 This is because measurements of photoelectron angular distributions (PADs) of clusters are not so common and the modelling of cluster PADs is demanding. 5,10,11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Typically, a prerequisite for the observation of magic numbers in the photoelectron anisotropy is a high cluster symmetry that results in orbitals with high fractional scharacter. 10,13,14,24 In our recent studies, 10,24 we reported the first observation of magic numbers in the photoelectron anisotropy of solvated electrons in Na-doped clusters of dimethyl ether, ammonia, methanol and water.…”