Correlation-bound anions of NaCl clusters

Abstract

In the past a variety of electron binding motifs has been identified for sodium chloride cluster anions. As for all of these clusters the excess electron is predicted to be bound in self-consistent-field calculations, the different binding mechanisms can be understood in terms of a one-electron potential largely due to the permanent multipole moments of the neutral cluster. Here we investigate a new class of (NaCl)(N)(-) anion that is predicted to be bound only after electron correlation has been taken into account. Correlation-bound states of the trimer, (NaCl)(3)(-), and tetramer, (NaCl)(4)(-), are characterized using Green's function and an equation-of-motion coupled-cluster method, and the computed electron binding energies as well as the distributions of the excess electrons as inferred from natural orbitals of the coupled-cluster calculations are compared with that of dipole-bound, quadrupole-bound, and defectlike (NaCl)(N)(-) anions. For the (NaCl)(4)(-) tetramer anion the correlation-bound state is predicted to represent the most stable isomer. Our results provide a sensitive test case for the development of improved one-electron model potentials for excess electrons bound to alkali halide clusters, and suggest that cluster abundance as inferred from peak intensities of photoelectron spectra is not directly related to the relative stability of the clusters.

Characterizing the excess electron of Li(NH3)4

“…The Aug-cc-pCVDZ basis set was used for all calculations. ciated with excess electrons is well known, 16,23 and while it can be dramatic in weakly bound systems, it is small for all systems considered here. More surprising are the small differences between orbital-based distributions and the related spin densities.…”

Observation and ultrafast dynamics of a nonvalence correlation-bound state of an anion

“…Correlation forces tend to be larger in highly polarizable systems, and calculations have predicted nonvalence CBSs for a number of cluster systems: (NaCl) n − ( n = 3 and 4) ( 20 ), (C 6 F 6 ) 2 − ( 10 ), (C 24 H 12 ) 2 − ( 11 ), (Xe) n − ( n = 5 to 7) ( 21 ), (NH 3 ) 6 − ( 22 ), and (H 2 O) 24 − (and likely other water cluster anions) ( 23 , 24 ). There is a belief that correlation forces are a key ingredient in defining the structure of solvated electrons ( 25 ) and controlling electron mobility in liquid Xe ( 26 ).…”

Evidence of Electron Capture of an Outgoing Photoelectron Wave by a Nonvalence State in (C6F6)n–

“…[3][4][5] Beyond these electrostatic interactions, correlation forces can also bind electrons, leading to so-called non-valence correlation-bound states. [6][7][8][9][10][11][12][13] In reality, it is often a combination of these interactions that bind the electron in a very diffuse non-valence orbital. 2 The binding energy of such an orbital is typically very small, less than a few 100 meV.…”