Ab initio study of superalkalis. First ionization potentials and thermodynamic stability

Abstract

The equilibrium geometries and fundamental frequencies of the Li2F+,

Anionic and Neutral States of Li3O

“…Theoretical predictions of the adiabatic and vertical ionization potential produced 3.55 and 3.45 eV, respectively [10,11], far outside the range of experimental values [71, although the theoretical dissociation energy of 47.1 kcal/mol [10] agrees well with the experimental prediction.…”

“…The neutral Li30 has already been studied both experimentally [7] and theoretically [8][9][10][11]. Wu at al.…”

“…In addition, it is a promising candidate for being a "superalkali", (i.e., a molecular system whose first ionization potential is smaller than that of the Cs atom [9][10][11]). Both of these unusual chemical features are related to the nature of the highest occupied molecular orbital (HOMO).…”

“…Early predictions of a C2, equilibrium structure for Li 3 0 [8] have not been confirmed in more advanced calculations [13,10] which indicated a D3h structure, similar to that of Li30+. Theoretical predictions of the adiabatic and vertical ionization potential produced 3.55 and 3.45 eV, respectively [10,11], far outside the range of experimental values [71, although the theoretical dissociation energy of 47.1 kcal/mol [10] agrees well with the experimental prediction.…”

Low ionization potentials of Na4OCN superalkali molecules

“…The superalkalies belong to a group of hypervalent or hypermetalated molecules. This term describes ML k+n species (where L is an alkali metal atom, k is the maximum formal valence of the central atom M, and n≥1) [1,[6][7][8][9] containing two or more metal atoms in stoichiometries that exceed normal valence expectations. The strong bonding interactions among the alkali metal "ligands" (L) which help to offset the octet-ruleviolating structure and antibonding L-M interactions are believed to be the major contributions to both the structure and stability of these species [1,[6][7][8][9][10][11][12][13][14][15][16].…”