Trends in MH2n+ ion–quadrupole complexes (M = Li, Be, Na, Mg, K, Ca; n = 1, 2) using ab initio methods

摘要: The ground state potential energy surfaces (PESs) of MH2n+ (M = Li, Be, Na, Mg, K, Ca; n 1, 2) have been investigated using relativistically corrected, coupled-cluster (CC) and multi-reference configuration interaction (MRCI) methods. PESs for MH2+ K) exhibit global minima corresponding to C2v symmetry equilibrium structures, with local D∞h C∞v states. Conversely, the LiH22+, NaH22+ KH22+ are repulsive. In all cases, states resulting from insertion Mn+ into H2 moiety were significantly higher in than co-linear It is generally assumed a priori that these species result between metal ion charge quadrupole moment moiety. However, analysis functional Δαα(R(Mn+–H2)) αα(MH2n+) − αα(Mn+) (which effectively difference traceless moments (αα) isolated computed MRCI) as function Mn+–H2 distance demonstrates maximum Δαα along molecular C2 axis necessary formation thermodynamically stable complex. concluded topology provides convenient indicator stability such ion–quadrupole complexes.